Method of reducing biofilms

ABSTRACT

The present invention relates to methods of eliminating, reducing or preventing bacterial biofilms by means of a fusion protein comprising an endolysin, an autolysin or a bacteriocin to which a peptide with membrane or LPS disrupting activity is fused. Further, the present invention relates to fusion proteins for use as a medicament, in particular for the treatment or prevention of Gram-negative and/or Gram-positive bacterial infections associated with bacterial biofilm, as diagnostic means, disinfectant or as cosmetic substance. The present invention also relates to the removal or reduction or prevention of Gram-negative and/or Gram-positive bacterial contamination associated with bacterial biofilm of foodstuff, of food processing equipment, of food processing plants, of surfaces coming into contact with foodstuff, of medical devices, of surfaces in hospitals and surgeries. Furthermore, the present invention relates to the use of said fusion protein as a diagnostic means in medicinal, food or feed or environmental diagnostic associated with bacterial biofilm.

This application is a national phase application under 35 U.S.C. §371 of International Application No. PCT/EP2011/056657 filed 27 Apr. 2011, which claims priority to European Application No. 10 161 170.5 filed on 27 Apr. 2010. The entire text of each of the above-reference disclosures is specifically incorporated herein by reference without disclaimer.

The present invention relates to methods of eliminating, reducing or preventing bacterial biofilms by means of a fusion protein comprising an endolysin, an autolysin or a bacteriocin to which a peptide with membrane or LPS disrupting activity is fused. Further, the present invention relates to fusion proteins for use as a medicament, in particular for the treatment or prevention of Gram-negative and/or Gram-positive bacterial infections associated with bacterial biofilm, as diagnostic means, disinfectant or as cosmetic substance. The present invention also relates to the removal or reduction or prevention of Gram-negative and/or Gram-positive bacterial contamination associated with bacterial biofilm of foodstuff, of food processing equipment, of food processing plants, of surfaces coming into contact with foodstuff, of medical devices, of surfaces in hospitals and surgeries. Furthermore, the present invention relates to the use of said fusion protein as a diagnostic means in medicinal, food or feed or environmental diagnostic associated with bacterial biofilm.

Endolysins are peptidoglycan hydrolases encoded by bacteriophages (or bacterial viruses). They are synthesized during late gene expression in the lytic cycle of phage multiplication and mediate the release of progeny virions from infected cells through degradation of the bacterial peptidoglycan. They are either β-(1,4)-glycosylases (lysozymes), transglycosylases, amidases or endopeptidases. Antimicrobial application of endolysins was already suggested in 1991 by Gasson (GB2243611). Although the killing capacity of endolysins has been known for a long time, the use of these enzymes as antibacterials was ignored due to the success and dominance of antibiotics. Only after the appearance of multiple antibiotic resistant bacteria this simple concept of combating human pathogens with endolysins received interest. A compelling need to develop totally new classes of antibacterial agents emerged and endolysins used as ‘enzybiotics’—a hybrid term of ‘enzymes’ and ‘antibiotics’—perfectly met this need. In 2001, Fischetti and coworkers demonstrated for the first time the therapeutic potential of bacteriophage C1 endolysin towards group A streptococci (Nelson et al., 2001). Since then many publications have established endolysins as an attractive and complementary alternative to control bacterial infections, particularly by Gram-positive bacteria.

Subsequently different endolysins against other Gram-positive pathogens such as Streptococcus pneumoniae (Loeffler et al., 2001), Bacillus anthracis (Schuch et al., 2002), S. agalactiae (Cheng et al., 2005) and Staphylococcus aureus (Rashel et al, 2007) have proven their efficacy as enzybiotics. Nowadays, the most important challenge of endolysin therapy lies in the insensitivity of Gram-negative bacteria towards the exogenous action of endolysins, since the outer membrane shields the access of endolysins from the peptidoglycan. This currently prevents the expansion of the range of effective endolysins to important Gram-negative pathogens.

Gram-negative bacteria possess an outer membrane, with its characteristic asymmetric bilayer as a hallmark. The outer membrane bilayer consists of an inner monolayer containing phospholipids (primarily phosphatidyl ethanolamine) and an outer monolayer that is mainly composed of a single glycolipid, lipopolysaccharide (LPS). There is an immense diversity of LPS structures in the bacterial kingdom and the LPS structure may be modified in response to prevailing environmental conditions. The stability of the LPS layer and interaction between different LPS molecules is mainly achieved by the electrostatic interaction of divalent ions (Mg²⁺, Ca²⁺) with the anionic components of the LPS molecule (phosphate groups in the lipid A and the inner core and carboxyl groups of KDO). Therefore, the cation-binding sites are essential for the integrity of the outer membrane (Vaara, 1992). Polycationic agents such as poly-L-lysine polymers (of at least 20 residues) increase the outer membrane permeability by displacement of these stabilizing divalent cations. In addition, they exert a so-called ‘self-promoted uptake’ mechanism (Hancock and Wong, 1984). Due to their bulkiness, they disrupt the normal barrier function of the outer membrane and create transient cracks, promoting their own uptake (Vaara and Vaara, 1983). Furthermore, the dense and ordered packing of the hydrophobic moiety of lipid A, favored by the absence of unsaturated fatty acids, forms a rigid structure with high viscosity. This makes it less permeable for lipophilic molecules and confers additional stability to the outer membrane (OM).

In contrast to Gram-negative bacteria, Gram-positive bacteria do not possess an outer membrane. The cytoplasmic membrane is surrounded by an up to 25 nm thick layer of peptidoglycan (which is only up to 5 nm for Gram-negative bacteria) which forms the cell wall. Main purpose of the cell wall of Gram-positives is to maintain bacterial shape and to counteract the internal bacterial cell pressure. Peptidoglycan, or murein, is a polymer consisting of sugars and amino acids. The sugar component consists of alternating residues of β-(1,4) linked N-acetylglucosamine and N-acetylmuramic acid residues compose the sugar components. A peptide chain of three to five amino acids is attached to the N-acetylmuramic acid. The peptide chain can be cross-linked to the peptide chain of another strand forming a 3D mesh-like layer. The peptide chain may contain D- and L-amino acid residues and the composition may vary for different bacteria.

Most Gram-negative bacteria, as well as many Gram-positive bacteria develop a bacterial biofilm. Biofilm is defined as an aggregate or association of microorganisms, which adhere to a surface. The adherent bacteria are often surrounded and protected by an extracellular polymer substance which is produced by the Gram-negative and Gram-positive bacteria. Due to the biofilm the bacteria are much more resistant to antimicrobial substances like antibiotics, disinfectants and cell wall degrading enzymes. In addition, the treatment of biofilms is currently not feasible because the extracellular polymer substance protects itself against degradation by antimicrobial substances, disinfectants or biofilm degrading substances.

Thus, there is a need for methods of eliminating, reducing or preventing bacterial biofilms.

This object is solved by the subject matter defined in the claims.

The following figures illustrate the present invention.

FIG. 1 is a schematic overview showing plasmid construction for recombinant production of (POLY)^(n)-gp144 ((POLY)^(n)-KZ144). Previously, pEXP5CT/POLY-gp144 (pEXPSCT/POLY-KZ144) was constructed by a tail PCR (with the BamHI restriction site and first polycation cassette in the 5′ tail primer). The plasmid was linearized with BamHI, dephosphorylated and ligated with a cassette containing overhanging BamHI ends. This cassette originates from the hybridization of two complementary oligonucleotides and encodes 9 positively charged residues. One additional positive arginine residue is created at the junction site between the first and second cassette, together with a serine. Longer pEXP5CT/(POLY)^(n)-gp144 (pEXP5CT/(POLY)^(n)-KZ144) variants were constructed similarly by repeated cycles.

FIG. 2 shows the expression and secretion of POLY-gp144 by Pichia pastoris. An amount of 30 μl supernatant of a P. pastoris X33 expression culture [after 1 day (square), 3 days (triangle) and 4 days (circle)] is added to 270 μl chloroform-permeabilized P. aeruginosa PAO1p cells. The buffer conditions were the optimal enzymatic conditions of POLY-gp144 (KH₂PO₄/K₂HP0₄) I=120 mM pH 6.2). Subsequently, the optical density was spectrophotometrically recorded. A drop in optical density indicates the secretion of a muralytic enzyme by P. pastoris. As a negative control, P. pastoris X33 without expression plasmid is included (diamond).

FIG. 3 shows in a graphical representation the antibacterial activity of the unmodified phiKZgp144 and ELgp188 endolysins, of the modified endolysin variants POLY-gp144 and POLY-gp188 comprising a peptide comprising 9 positively charged amino acid residues and of the modified variants (POLY)²-gp144 and (POLY)²-gp188 comprising a peptide comprising 18 positively charged amino acid residues on Pseudomonas aeruginosa PAO1p cells. The error bars render the standard deviations of the mean.

FIG. 4 shows a picture of a Coomassie-stained SDS-PAGE showing the results of the expression and purification of the unmodified endolysin PSP3gp10 and its modified endolysin variant PKPSP3gp10. The lane LMW pertains to a size marker (LMW ladder). The following three lanes pertain to protein fractions of the purified protein in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 500 mM imidazole) after Ni²⁺ affinity chromatography. The lane FT pertains to the flow through and the lane W to waste fractions. Only minor secondary bands are visible in the purified protein fractions, indicating the high purity of the recombinant proteins (>90%).

FIGS. 5 A to D show in a graphic representation the antibacterial activities of unmodified PSP3gp10 and the modified PKPSP3gp10 in different compositions on several exponential growing Gram-negative bacteria after an incubation at room temperature and without shaking. Each species of Gram-negative bacteria was incubated for 30 minutes with a composition comprising 0.5 mM EDTA but no endolysin, with a composition comprising 1.315 μM unmodified PSP3gp10 but no EDTA, with a composition comprising 1.315 μM modified PKPSP3gp10 but no EDTA, with a composition comprising 1.315 μM unmodified PSP3gp10 and 0.5 mM EDTA and with a composition comprising 1.315 μM modified PKPSP3gp10 and 0.5 mM EDTA. In FIG. 5 A the antibacterial activity on P. aeruginosa PAO1p cells is represented, in FIG. 5 B the antibacterial activity on P. aeruginosa Br667 cells, in FIG. 5 C the antibacterial activity on E. coli WK 6 cells and in FIG. 5 D the antibacterial activity on Salmonella typhimurium cells. “Δ” gives the difference of activity between the respective PSP3gp10 and PKPSP3gp10 samples. The error bars render the standard deviations of the mean.

FIG. 6 shows a picture of a Coomassie-stained SDS-PAGE showing the results of the expression and purification of the unmodified endolysin P2gp09 and its modified endolysin variant PKP2gp09. The lane LMW pertains to a size marker (LMW ladder). The following three lanes pertain to protein fractions of the purified protein in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 500 mM imidazole) after Ni²⁺ affinity chromatography. The lane FT pertains to the flow through and the lane W to waste fractions. Only minor secondary bands are visible in the purified protein fractions, indicating the high purity of the recombinant protein (>95%).

FIGS. 7 A to F show in a graphic representation the antibacterial activities of unmodified P2gp09 and the modified PKP2gp09 in different compositions on several exponential growing Gram-negative bacteria after an incubation at room temperature and without shaking. Each species of Gram-negative bacteria was incubated for 30 minutes with a composition comprising 0.5 mM EDTA but no endolysin, with a composition comprising 1.315 μM unmodified P2gp09 but no EDTA, with a composition comprising 1.315 μM modified PKP2gp09 but no EDTA, with a composition comprising 1.315 μM unmodified P2gp09 and 0.5 mM EDTA and with a composition comprising 1.315 μM modified PKP2gp09 and 0.5 mM EDTA. In FIG. 7 A the antibacterial activity on P. aeruginosa PAO1p cells is represented, in FIG. 7 B the antibacterial activity on P. aeruginosa Br667 cells, in FIG. 7 C the antibacterial activity on E. coli WK 6 cells, in FIG. 7 D the antibacterial activity on Burkholderia pseudomallei cells, in FIG. 7 E the antibacterial activity on Pseudomonas putida G1 cells and in FIG. 7 F the antibacterial activity on Salmonella typhimurium LT2 (SGSC No 2317) cells. “Δ” gives the difference of activity between the respective P2gp09 and PKP2gp09 samples. The error bars render the standard deviations of the mean.

FIG. 8 shows a picture of a Coomassie-stained SDS-PAGE showing the results of the expression and purification of the unmodified endolysin OBPgpLYS and its modified endolysin variant PKOBPgpLYS. The lane LMW pertains to a size marker (LMW ladder). The following three lanes pertain to protein fractions of the purified protein in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 500 mM imidazole) after Ni²⁺ affinity chromatography. The lane FT pertains to the flow through and the lane W to waste fractions. Only minor secondary bands are visible in the purified protein fractions, indicating the high purity of the recombinant proteins (>90%).

FIGS. 9 A to F show in a graphic representation the antibacterial activities of different compositions of unmodified OBPgpLYS and the modified PKOBPgpLYS on several exponential growing Gram-negative bacteria after an incubation at room temperature and without shaking. Each species of Gram-negative bacteria was incubated for 30 minutes with a composition comprising 0.5 mM EDTA but no endolysin, with a composition comprising 1.315 μM unmodified OBPgpLYS but no EDTA, with a composition comprising 1.315 μM modified PKOBPgpLYS but no EDTA, with a composition comprising 1.315 μM unmodified OBPgpLYS and 0.5 mM EDTA and with a composition comprising 1.315 μM modified PKOBPgpLYS and 0.5 mM EDTA. In FIG. 9 A the antibacterial activity on Escherichia coli WK6 cells is represented, in FIG. 9 B the antibacterial activity on Salmonella typhimurium LT2 (SGSC No 2317) cells, in FIG. 9 C the antibacterial activity on Pseudomonas aeruginosa PAO1p cells, in FIG. 9 D the antibacterial activity on Pseudomonas aeruginosa Br667 cells, in FIG. 9 E the antibacterial activity on Pseudomonas putida G1 cells and in FIG. 9 F the antibacterial activity on Burkholderia pseudomallei cells. “Δ” gives the difference of activity between the respective OBPgpLYS and PKOBPgpLYS samples. The error bars render the standard deviations of the mean.

FIGS. 10 A and B show in a graphic representation the biofilm reducing activities of PolyKZ144 (Art-014) on a mucoid growing clinical isolate of Pseudomonas aeruginosa 2573 (Source Uniklinikum Regensburg, nicht näher definiert). Pseudomonas aeruginosa 2573 was grown at least 24 hours at 37° C. in a polystyrene microtiter plate to allow biofilm formation. To visualize the biofilm content crystal violet staining was performed. In FIG. 10 A, the biofilm was then incubated with either Alginate lyase (10 u/ml) or PolyKZ144 (50 μg/ml). The effect of both enzymes was compared to either biofilm untreated or biofilm washed and reincubated in LB-medium as controls. In FIG. 10 B the effect of PolyKZ144 was compared to either biofilm untreated or biofilm washed and reincubated in LB-medium as controls and a non mucoid growing E. coli lab strains to indicated unspecific background staining.

FIGS. 11 A to G show in a graphic representation the biofilm reducing activities of several fusion proteins on different Gram-positive and Gram-negative bacterial strains. Staphylococcus aureus KS13 (A and B), Listeria monocytogenes Scott A (C), Acinetobacter baumannii DSMZ30007 (D), Pseudomonas aeruginosa 2572 (E, F) and Pseudomonas aeruginosa 2573 (G) was grown at least 24 hours at 37° C. in a polystyrene microtiter plate to allow biofilm formation. To visualize the biofilm content crystal violet staining was performed. In FIG. 11 A, the biofilm was then incubated with either PK-Peptide (1.25 μg/well) or the endolysin Ply2638 (25 μg/well) or the fusion protein Ply2638-PK (25 μg/well). The effect of the peptide, the endolysin and the fusion protein was compared to biofilm untreated (one part protein buffer to one part 2×LB without NaCl) indicated by LB. In FIG. 11 B, the biofilm was then incubated with either the bacteriocin Lysostaphin (18 μg/well) or the bacteriocin variant PK-Lysostaphin (18 μg/well). The effect of the bacteriocin and the bacteriocin variant was compared to biofilm untreated (one part protein buffer to one part 2×LB without NaCl) indicated by LB. In FIG. 11 C, the biofilm was then incubated with the modified endolysin variant Pentapeptide-Ply511 (25 μg/well). The effect of the modified endolysin variant was compared to biofilm untreated (one part protein buffer to one part 2×LB without NaCl) indicated by LB. In FIGS. 11 D and E, the biofilm was then incubated with either PK-Peptide (1.25 μg/well) or the endolysin OBP (25 μg/well) or the modified endolysin variant PK-OBP (25 μg/well). The effect of the peptide, the endolysin and the modified endolysin variant was compared to biofilm untreated (one part protein buffer to one part 2×LB without NaCl) indicated by LB. In FIGS. 11 F and G, the biofilm was then incubated with either the endolysin KZ144 (50 μg/well) or the modified endolysin variant SMAP29-KZ144 (50 μg/well). The effect of the peptide, the endolysin and the modified endolysin variant was compared to biofilm untreated (one part protein buffer to one part 2×LB without NaCl) indicated by LB.

The term “protein” as used herein refers synonymously to the term “polypeptide”. The term “protein” as used herein refers to a linear polymer of amino acid residues linked by peptide bonds in a specific sequence. The amino-acid residues of a protein may be modified by e.g. covalent attachments of various groups such as carbohydrates and phosphate. Other substances may be more loosely associated with the polypeptide chains, such as heme or lipid, giving rise to the conjugated proteins which are also comprised by the term “protein” as used herein. There are various ways in which the polypeptide chains fold have been elucidated, in particular with regard to the presence of alpha helices and beta-pleated sheets. The term “protein” as used herein refers to all four classes of proteins being all-alpha, all-beta, alpha/beta and alpha plus beta. Moreover, the term “protein” refers to a complex, wherein the complex refers to a homomer.

The term “fusion protein” as used herein refers to an expression product resulting from the fusion of two nucleic acid sequences. Such a protein may be produced, e.g. in recombinant DNA expression systems or by chemical cross-linking. Moreover, the term “fusion protein” as used herein refers to a fusion of a first amino acid sequence, in particular an endolysin, an autolysin or a bacteriocin and/or other peptidoglycan hydrolase, with a second or further amino acid sequence. The second or further amino acid sequence is preferably a peptide, in particular a cationic, apolycationic, a hydrophobic, an amphiphatic and/or an antimicrobial peptide. Preferably, said second and/or further amino acid sequence is foreign to and not substantially homologous with any domain of the first amino acid sequence.

The term “modified endolysin variant” is used herein synonymously with the term “endolysin variant”. Both terms refer to a fusion protein comprising an endolysin and a peptide, in particular a cationic, a polycationic, a hydrophobic, an amphiphatic and/or an antimicrobial peptide.

The term “modified bacteriocin variant” is used herein synonymously with the term “bacteriocin variant”. Both terms refer to a fusion protein comprising a bacteriocin and a peptide, in particular a cationic, a polycationic, a hydrophobic, an amphiphatic and/or an antimicrobial peptide.

The term “modified autolysin variant” is used herein synonymously with the term “autolysin variant”. Both terms refer to a fusion protein comprising an autolysin and a peptide, in particular a cationic, a polycationic, a hydrophobic, an amphiphatic and/or an antimicrobial peptide.

The term “peptide stretch” as used herein refers to any kind of peptide linked to a protein such as an endolysin, bacteriocin or autolysin. In particular the term “peptide stretch” as used herein refers to a cationic peptide, a polycationic peptide, an amphiphatic peptide, a hydrophobic peptide and/or an antimicrobial peptide. However, a peptide stretch in the meaning of the present invention does not refer to His-tags, preferably His₅-tags, His₆-tags, His₇-tags, His₈-tags, His₉-tags, His₁₀-tags, His₁₁-tags, His₁₂-tags, His₁₆-tags and His₂₀-tags, Strep-tags, Avi-tags, Myc-tags, Gst-tags, JS-tags, cystein-tags, FLAG-tags or other tags known in the art, thioredoxin or maltose binding proteins (MBP). The term “tag” in contrast to the term “peptide stretch” as used herein refers to a peptide which can be useful to facilitate expression and/or affinity purification of a polypeptide, to immobilize a polypeptide to a surface or to serve as a marker or a label moiety for detection of a polypeptide e.g. by antibody binding in different ELISA assay formats as long as the function making the tag useful for one of the above listed facilitation is not caused by the positively charge of said peptide. However, the His₆-tag may, depending on the respective pH, also be positively charged, but is used as affinity purification tool as it binds to immobilized divalent cations and is not used as a peptide stretch according to the present invention.

The term “peptide” as used herein refers to short peptides consisting of from about 2 to about 100 amino acid residues, more preferably from about 4 to about 50 amino acid residues, more preferably to about 5 to 30 amino acid residues, wherein the amino group of one amino acid residue is linked to the carboxyl group of another amino acid residue by a peptide bond. A peptide may have a specific function. A peptide can be a naturally occurring peptide or a synthetically designed and produced peptide. The peptide can be, for example, derived or removed from a native protein by enzymatic or chemical cleavage, or can be prepared using conventional peptide synthesis techniques (e.g., solid phase synthesis) or molecular biology techniques (see Sambrook, J. et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989)). Preferred synthetically produced peptides are e.g. cationic, polycationic, amphipathic or hydrophobic peptides. Preferred naturally occurring peptides are e.g. antimicrobial peptides.

As used herein, the term “cationic peptide” refers to a peptide having positively charged amino acid residues. Preferably a cationic peptide has a pKa-value of 9.0 or greater. Typically, at least four of the amino acid residues of the cationic peptide can be positively charged, for example, lysine or arginine. “Positively charged” refers to the side chains of the amino acid residues which have a net positive charge at about physiological conditions. The term “cationic peptide” as used herein refers also to polycationic peptides.

The term “polycationic peptide” as used herein refers to a synthetically designed and produced peptide composed of mostly positively charged amino acid residues, in particular lysine, arginine and/or histidine residues, more preferably lysine and/or arginine residues. A peptide is composed of mostly positively charged amino acid residues if at least about 20, 30, 40, 50, 60, 70, 75, 80, 85, 90, 95 or about 100% of the amino acid residues are positively charged amino acid residues, in particular lysine and/or arginine residues. The amino acid residues being not positively charged amino acid residues can be neutrally charged amino acid residues and/or negatively charged amino acid residues and/or hydrophobic amino acid residues. Preferably the amino acid residues being not positively charged amino acid residues are neutrally charged amino acid residues, in particular serine and/or glycine.

The term, “antimicrobial peptide” (AMP) as used herein refers to any naturally occurring peptide that has microbicidal and/or microbistatic activity on for example bacteria, viruses, fungi, yeasts, mycoplasma and protozoa. Thus, the term “antimicrobial peptide” as used herein refers in particular to any peptide having anti-bacterial, anti-fungal, anti-mycotic, anti-parasitic, anti-protozoal, anti-viral, anti-infectious, anti-infective and/or germicidal, algicidal, amoebicidal, microbicidal, bactericidal, fungicidal, parasiticidal, protozoacidal, protozoicidal properties, in particular sushi peptides and defensin. The antimicrobial peptide may be a member of the RNAse A super family, a defensin, cathelicidin, granulysin, histatin, psoriasin, dermicidine or hepcidin. The antimicrobial peptide may be naturally occurring in insects, fish, plants, arachnids, vertebrates or mammals.

Preferably the antimicrobial peptide may be naturally occurring in insects, fish, plants, arachnids, vertebrates or mammals. Preferably the antimicrobial peptide may be naturally occurring in radish, silk moth, wolf spider, frog, preferably in Xenopus laevis, Rana frogs, more preferably in Rana catesbeiana, toad, preferably Asian toad Bufo bufo gargarizans, fly, preferably in Drosophila, more preferably in Drosophila melanogaster, in Aedes aegypti, in honey bee, bumblebee, preferably in Bombus pascuorum, flesh fly, preferably in Sarcophaga peregrine, scorpion, horseshoe crab, catfish, preferably in Parasilurus asotus, cow, pig, sheep, porcine, bovine, monkey and human.

The term “sushi peptide” as used herein refers to complement control proteins (CCP) having short consensus repeats. The sushi module of sushi peptides functions as a protein-protein interaction domain in many different proteins. Peptides containing a Sushi domain have been shown to have antimicrobial activities. Preferably, sushi peptides are naturally occurring antimicrobial peptides.

The term “amphiphatic peptide” as used herein refers to synthetic peptides having both hydrophilic and hydrophobic functional groups. Preferably, the term “amphiphatic peptide” as used herein refers to a peptide having a defined arrangement of hydrophilic and hydrophobic groups e.g. amphiphatic peptides may be e.g. alpha helical, having predominantly non polar side chains along one side of the helix and polar residues along the remainder of its surface.

The term “hydrophobic group” as used herein refers to chemical groups such as amino acid side chains which are substantially water insoluble, but soluble in an oil phase, with the solubility in the oil phase being higher than that in water or in an aqueous phase. In water, amino acid residues having a hydrophobic side chain interact with one another to generate a nonaqueous environment. Examples of amino acid residues with hydrophobic side chains are valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues.

The term “endolysin” as used herein refers to an enzyme which is suitable to hydrolyse bacterial cell walls. “Endolysins” comprise at least one “enzymatically active domain” (EAD) having at least one of the following activities: endopeptidase, N-acetyl-muramoyl-L-alanine-amidase (amidase), N-acetyl-muramidase, N-acetyl-glucosaminidase (lysozyme) or transglycosylases. In addition, the endolysins may contain also regions which are enzymatically inactive, and bind to the cell wall of the host bacteria, the so-called CBDs (cell wall binding domains). The endolysin may contain one, two or more CBDs. However, the term “endolysin” as used herein refers also to enzymes having at least one EAD but no CBDs. Generally, the cell wall binding domain is able to bind different components on the surface of bacteria. Preferably, the cell wall binding domain is a peptidoglycan binding domain and binds to the bacteria's peptidoglycan.

The term “cell wall” as used herein refers to all components that form the outer cell enclosure of the Gram-positive and Gram-negative bacteria and thus guarantee their integrity. In particular, the term “cell wall” as used herein refers to peptidoglycan, the outer membrane of the Gram-negative bacteria with the lipopolysaccharide, the bacterial cell membrane, but also to additional layers deposited on the peptidoglycan as e.g. capsules, outer protein layers or slimes.

The term “autolysins” as used herein refers to enzymes related to endolysins but encoded by bacteria and involved in e.g. cell division and cell wall metabolism. An overview of autolysins can be found in “Bacterial peptidoglycan (murein) hydrolases. Vollmer W, Joris B, Charlier P, Foster S. FEMS Microbiol Rev. 2008 March; 32(2):259-86”.

The term “bacteriocin” as used herein refers to protein-like, polypeptide-like or peptide-like substances which are able to inhibit the growth of other bacteria. Some bacteriocins are capable of degrading bacterial cell walls like Lysostaphin (degrading Staphylococcus cell walls), Mutanolysin (degrading Streptococcus cell walls) and Enterolysin (degrading Enterococcus cell walls). Preferably said inhibition is specifically by means of absorption of said other bacteria to specific receptors of the bacteriocin. In general, bacteriocins are produced by microorganisms. However, the term “bacteriocin” as used herein refers both to an isolated form procuded by a microorganism or to a synthetically produced form, and refers also to variants which substantially retain the activities of their parent bacteriocins, but whose sequences have been altered by insertion or deletion of one or more amino acid residues.

The term “EAD” as used herein refers to the enzymatically active domain of an endolysin. The EAD is responsible for hydrolysing bacterial peptidoglycans. It exhibits at least one enzymatic activity of an endolysin. The EAD can also be composed of more than one enzymatically active module. The term “EAD” is used herein synonymously with the term “catalytic domain”.

The term “deletion” as used herein refers to the removal of 1, 2, 3, 4, 5 or more amino acid residues from the respective starting sequence.

The term “insertion” or “addition” as used herein refers to the insertion or addition of 1, 2, 3, 4, 5 or more amino acid residues to the respective starting sequence.

The term “substitution” as used herein refers to the exchange of an amino acid residue located at a certain position for a different one.

The term “biofilm” as used herein refers to an aggregate of bacterial microorganisms in which bacterial cells adhere to each other and/or to a surface. These adherent cells are often covered with a matrix of extracellular polymeric substance (EPS), which is produced by the cells. Biofilm EPS, is composed of extracellular DNA, proteins, and polysaccharides. These biofilms may form on any living or non-living surfaces, in particular on both on solid surfaces as colonies and on liquid surfaces as pellicles. Microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism.

The present invention relates to methods of eliminating, reducing or preventing of a bacterial biofilm comprising the steps of:

-   -   a) providing a fusion protein comprising an enzyme having the         activity of degrading the cell wall of Gram-negative and/or         Gram-positive bacteria to which a peptide with membrane or LPS         disrupting activity is fused; and     -   b) contacting a material, liquid, surface or biological material         with said fusion protein.

Preferably, the present invention relates to methods of eliminating, reducing or preventing of a bacterial biofilm comprising the steps of:

-   -   c) providing a fusion protein comprising an endolysin, autolysin         or bacteriocin to which a peptide with membrane or LPS         disrupting activity is fused; and     -   d) contacting a material, liquid, surface or biological material         with said fusion protein.

The term “providing” a fusion protein according to the present invention refers either to the mere taking and using of the fusion protein according to the present invention or to the generating and purification of such fusion protein prior to the use according to the present invention.

Preferably, the material is a stone, rocks, soil, sediments, food, feed or cosmetics. Preferably, the liquid is water, such as drinking water, ground water or waste water, hot springs, seas, lakes, rivers, any kind of aequous systems, cleaning and storage solutions of contact lenses, dentures, implants, protheses, or braces.

Preferably, the biological material is any substance derived or obtained from a living organism, in particular plants and mammals, preferably humans, e.g. cells, tissues, organs, blood, blood components and body liquids. Preferably, cells are e.g. nucleated cells or anucleated cells. Cells can be derived from any organ in particular hepatocytes, smooth muscle cells, endothelial cells, keratinocytes, islet cells, stem cells (adult and neonatal, various tissues, or species origin), stem cell progenitor cells, cord blood cells, gametes (male and female), gamete progenitor cells, erythroblasts, leukoblasts, and chondroblasts. Tissues are e.g. mucous membranes, nerves, muscles, epithels, connective and supporting tissues, oral soft tissues and teeth. Organs are e.g. heart, heart valves, eye, ear, urinary tract, lungs, liver, kidney, biliary tract, prostate, nose, digestive tract, respiratory tract, gastrointestinal tract, brain and bone marrow. Preferred body liquids are urin, cerebrospinal fluid and lymph fluids.

Preferably, surfaces are solid biological or non-biotic surfaces. Preferred examples of surfaces are the surface of medical devices, in particular implants, protheses, cathethers, such as dental implants, urinary tract prostheses, peritoneal membrane and peritoneal dialysis catheters, indwelling catheters for hemodialysis and for chronic administration of chemotherapeutic agents (Hickman catheters), cardiac implants such as pacemakers, prosthetic heart valves, ventricular assist devices, synthetic vascular grafts and stents, internal fixation devices, percutaneous sutures and tracheal and ventilator tubing, as well as surfaces of industrial or potable water system piping and of natural aquatic systems.

Biofilms are formed by bacterial microorganisms in which bacterial cells adhere to each other and/or to a surface. Extracellular polymeric substances (EPS) excreted by the bacterial microorganisms of a biofilm form with water hydrogels, so that a slime-like matrix is formed. This matrix may also comprise gas bubbles and anorganic particles. Biofilm EPS, is composed of extracellular DNA, proteins, and polysaccharides. Besides the bacterial microorganisms other unicellular organisms may be integrated in the biofilm. Biofilms may occur by the settling of bacterial microorganisms to interfaces. Mostly, the biofilm is formed on water surfaces or on an interface to a solid phase. These biofilms may form on any living or non-living surfaces. In general all interfaces may be settled by biofilms. Biofilms are almost present everywhere, in soil and sediments, in ground water, on rocks, in desserts, in hot springs, on and in plants and animals, in particular on mucous membranes. Moreover, biofilms may occur on medical devices, such as implants, cathethers, endoscopes, protheses, instruments, and apparatus but also in cosmetics, food and feed. Biofilms may be also associated with infections, because in most cases the bacterial microorganisms form biofilm to be protected against the immune system. The formation of a biofilm ensures the long-term survival of the bacterial microorganisms. One example of an acute respiratory tract infection is the legionnaire's disease which is caused by swallowing or inhalation of clumps of legionella-biofilms detached from air or water pipes of heating or cooling systems. Also many food bacteria, like E. coli 0157:H7, Listeria monocytogenes, Yersinia enterocolitica, Salmonella spp. and Camphylobacter jejuni may form on food and devices biofilms which are then highly resistant to biocides, drought, heat, antibiotics and cleaning reagents. The microorganisms responsible for infections of implants, catheters and other medical devices may be coagulase-negative staphylococci, Staphylococcus aureus, Enterococcus faecalis, Streptococcus spp., Escherichia coli, Klebsiella pneumoniae, Acinetobacter spp., Proteus mirabilis, Pseudomonas aeruginsa and Candida spp. which are also associated with a broad spectrum of nosocomial infections. Typical bacterial infections associated with biofilms in humans are: wound infections, in particular wounds associated with diabetes mellitus, tonsillitis, osteomyelitis, bacterial endocarditis, sinusitis, infections of the cornea, urinary tract infection, infection of the biliary tract, infectious kidney stones, urethritis, prostatitis, catheter infections, middle-ear infections, formation of dental plaque, gingivitis, periodontitis, cystic fibrosis, and infections of permanent indwelling devices such as joint prostheses and heart valves.

The presence of biofilms may be determined by various tests, such as by the Tissue culture plate method (TCP) described in Christensen et al., J Clin Microbiol 22:996-1006 (1985), or by the Tube method (TM) as previously described by Christensen et al., Infect Immun 37:318-26 (1982), or by the Congo red Agar method (CRA) described by Freeman et al., J Clin Pathol 42:872-4 (1989). The biofilm may be quantified by using crystal violet assay (Peeters et al., J Microbiol Methods 72: 157-165 (2008)).

The fusion protein according to the present invention may influence the interaction of the bacteria forming a biofilm so that the cells are transferred in single planktonic cells which where then lysed by said fusion protein, consequently the biofilm is then degraded in part or totally. The influence of the fusion protein according to the present invention on the bacteria may also directly lyse the bacteria associated in a biofilm and thus, the biofilm is degraded in part or totally. Moreover, the fusion protein according to the present invention may prevent the formation of bacterial biofilms by lysing bacteria which are able to form a biofilm with other bacteria.

The fusion proteins according to the present invention relate preferably to endolysin variants, bacteriocin variants and autolysin variants.

Preferred fusion proteins according to the present invention comprise an endolysin, an autolysin or a bacteriocin fused to a peptide with lipopolysachharide (LPS) or in general membrane disrupting activity. LPS is a major component of the outer membrane of Gram-negative bacteria. It increases the negative charge of the cell membrane and protects the membrane from certain kinds of chemical attack. To a certain degree said LPS protects the membrane of Gram-negative bacteria also from endolysins added from outside of the bacteria. However, the LPS can be disrupted by peptides having a LPS disrupting activity as e.g. positively charged peptides. Moreover, said peptides may be involved in the outer membrane protein transport mechanism, a destabilisation of structural outer membrane proteins and/or in lipid-dependent destabilisation. The inventors of the present invention have surprisingly found, that a peptide having LPS disrupting activity or in general membrane disrupting activity promotes the passage of an endolysin, an autolysin or a bacteriocin fused to said peptide through the outer membrane of Gram-negative bacteria. After the promoted pass of the endolysin, autolysin or bacteriocin through the outer membrane of bacteria, the cell wall of the bacterium can be more easily be disrupted or desintegrated by the endolysin due to degradation of the peptidoglycan layer followed by osmotic lysis when the internal cell pressure of the bacterium cannot longer be resisted. The Gram-positive bacteria have a much thicker peptidoglycan layer than Gram-negative bacteria. Here the membrane disrupting activity of the fusion protein supports the lysis of the bacteria, by acting on the cytoplasmic membrane.

Thus, the present invention refers to methods of eliminating, reducing or preventing bacterial biofilms by means of fusion proteins composed of an enzyme, preferably an endolysin, an autolysin or a bacteriocin, having the activity of degrading the cell wall of Gram-negative and/or Gram-positive bacteria and a peptide with membrane disrupting activity, wherein said peptide is fused to the enzyme at the N- and/or C-terminus. Said fusion proteins according to the present invention are also called modified endolysin variants or simply endolysin variants or modified endolysins, modified autolysin variants or autolysin variants, modified bacteriocins or bacteriocin variants.

The endolysin part of the fusion protein is preferably encoded by bacteriophages specific for Gram-negative bacteria such as Gram-negative bacteria of bacterial groups, families, genera or species comprising strains pathogenic for humans or animals like Enterobacteriaceae (Escherichia, especially E. coli, Salmonella, Shigella, Citrobacter, Edwardsiella, Enterobacter, Hafnia, Klebsiella, especially K. pneumoniae, Morganella, Proteus, Providencia, Serratia, Yersinia), Pseudomonadaceae (Pseudomonas, especially P. aeruginosa, Burkholderia, Stenotrophomonas, Shewanella, Sphingomonas, Comamonas), Neisseria, Moraxella, Vibrio, Aeromonas, Brucella, Francisella, Bordetella, Legionella, Bartonella, Coxiella, Haemophilus, Pasteurella, Mannheimia, Actinobacillus, Gardnerella, Spirochaetaceae (Treponema and Borrelia), Leptospiraceae, Campylobacter, Helicobacter, Spirillum, Streptobacillus, Bacteroidaceae (Bacteroides, Fusobacterium, Prevotella, Porphyromonas), Acinetobacter, especially A. baumannii.

In another preferred embodiment, the endolysin of the fusion protein is encoded by bacteriophages specific for Gram-positive bacteria such as Gram-positive bacteria of bacterial groups, families, genera or species comprising strains pathogenic for humans or animals, in particular of the phylum Actinobacteria, in particular of the class Actinobacteridae, in particular of the order Actinomycetales, in particular of the families Actinomycineae: Actinomycetaceae (Actinomyces, Mobiluncus), Corynebacterineae: Mycobacteriaceae (Mycobacterium), Nocardiaceae, Corynebacteriaceae, Frankineae: Frankiaceae, Micrococcineae: Brevibacteriaceae and Propionibacteriaceae (Propionibacterium) and of the order Bifidobacteriales, in particular of the families Bifidobacteriaceae (Bifidobacterium, Falcivibrio, Gardnerella) and other subclasses: Acidimicrobidae, Coriobacteridae, Rubrobacteridae, Sphaerobacteridae; and of the phylum Firmicutes, in particular of the class Bacilli, in particular of the order Bacillales, in particular of the families: Bacillaceae (Bacillus), Listeriaceae (Listeria), Staphylococcaceae (Staphylococcus, Gemella, Jeotgalicoccus) and of the order Lactobacillales, in particular of the families: Enterococcaceae (Enterococcus), Lactobacillaceae (Lactobacillus, Pediococcus), Leuconostocaceae (Leuconostoc), Streptococcaceae (Lactococcus, Streptococcus) and of the class Clostridia, in particular of the order: Clostridiales (Clostridium, Peptostreptococcus, Selenomonas), Halanaerobiales and Thermoanaerobacterales, and of the class Tenericutes/Mollicutes, in particular of the order: Mycoplasmatales (Mycoplasma, Ureaplasma), Entomoplasmatales (Spiroplasma), Anaeroplasmatales (Erysipelothrix), Acholeplasmatales (Acholeplasma), Haloplasmatales (Haloplasma).

In another preferred embodiment, the autolysin or the bacteriocin of the fusion protein is encoded by Gram-negative or Gram-positive bacteria such as Gram-negative or Gram-positive bacteria of bacterial groups, families, genera or species comprising strains pathogenic for humans or animals as listed above.

Preferably, the endolysin part derives from a phage or a wild type endolysin as depicted in the following table 1:

phage publication Wild type endolysin predicted function of the endolysin φV10 Perry, L. L. and Applegate, B. M. PhiV10p30 chitinase FELS-1 McClelland, M. and Wilson, R. K. STM0907.Fels0 chitinase ε15 Kropinksi, A. M. and McConnel, M. R. epsilon15p25 chitinase YUA Ceyssens. P. (Laboratory for Gene YuA20 lytic transglycosylase (C)/1 transmembranair technology) domain (N) B3 Braid, M. D. and Kitts, C. L. ORF23 lytic transglycosylase (C)/2 transmembranair domains (N) BCEPμ Summer, E. J. and Young, R. BcepMu22 lytic transglycosylase (M)/1 transmembranair domain (N) F116 Byrne, M. and Kropinski, A. M. F116p62 muraminidase (T4-like) FELS-2 McClelland, M. and Wilson, R. K. STM2715.S.Fels2 muraminidase (T4-like) ES18 Casjens, S. R. and Hendrix, R. W. gp76 muraminidase (T4-like) SETP3 De Lappe, N and Cormican, M. SPSV3_gp23 muraminidase (T4-like) φECO32 Savalia, D and Severinov, K phi32_17 muraminidase (T4-like) HK022 Juhala, R and Hendrix, R. W. HK022p54 muraminidase (lambdalike) HK97 Juhala, R and Hendrix, R. W. HK97p58 muraminidase (lambdalike) HK620 Clark, A. J. and Dhillon, T. S. HK620p36 muraminidase (lambdalike) E1 Pickard, D. and Dougan, G VIP0007 muraminidase (lambdalike) SF6 Casjens, S and Clark, A. J. Sf6p62 muraminidase (lambdalike) SFV Allison, G. E. and Verma, N. K. R (SfVp40) muraminidase (lambdalike) BCEPC6B Summer, E J and Young, R. gp22 muraminidase (lambdalike) BCEPNAZGUL Summer, E J and Young, R. Nazgul38 muraminidase (lambdalike) P2 Christie, G. E. and Calender, R. K (P2p09) muraminidase (lambdalike) Wφ Christie, G. E. and Esposito, D. K (Wphi09) muraminidase (lambdalike) RV5 Kropinski, A. M. and Johnson rv5_gp085 muraminidase (lambdalike) JS98 Zuber, S and Denou, E. EpJS98_gp116 muraminidase (T4-like) 13A Savalia, D and Molineux, I. gp3.5 muramoyl-L-alanine amidase BA14 Savalia, D and Molineux, I. gp3.5 muramoyl-L-alanine amidase ECODS1 Savalia, D and Molineux, I. gp3.5 muramoyl-L-alanine amidase K1F Scholl, D and Merril, C CKV1F_gp16 muramoyl-L-alanine amidase T3 Pajunen, M. I. and Mollineux, I. J. T3p18 muramoyl-L-alanine amidase GH-1 Kropinski, A. M. and Kovalyova, I. V. gh-1p12 muramoyl-L-alanine amidase K11 Molineux, I. and Savalia, D. gp3.5 muramoyl-L-alanine amidase BIP-1 Liu, M and Miller, J. F. bip-1p02 lysozyme (N)/PG-binding domain (C) BMP-1 Liu, M and Miller, J. F. bmp-1pO2 lysozyme (N)/PG-binding domain (C) BPP-1 Liu, M and Miller, J. F. bpp2 lysozyme (N)/PG-binding domain (C) φCTX Nakayama, K and Hayashi, T. ORF12 PG-binding domain (N)/muramidase (C) BCEP43 Summer, E J and Young, R. Bcep43-27 PG-binding domain (N)/muramidase (C) BCEP781 Summer, E J and Young, R. Bcep781-27 PG-binding domain (N)/muramidase (C) BCEP1 Summer, E J and Young, R. Bcep1-28 PG-binding domain (N)/muramidase (C) BCEPNY3 Summer, E J and Young, R. BcepNY3gene26 PG-binding domain (N)/muramidase (C) φE12-2 DeShazer, D and Nierman, W. C. gp45 PG-binding domain (N)/muramidase (C) φ52237 DeShazer, D and Nierman, W. C. gp28 PG-binding domain (N)/muramidase (C) φP27 Recktenwald, J and Schmidt, H. P27p30 endopeptidase RB49 Monod, C and Krisch, H. M. RB49p102 endopeptidase φ1 Arbiol, C. and Comeau, A. M. phi1-p102 endopeptidase T5 Pankova, N. V. and Ksenzenko, V. N. lys (T5.040) endopeptidase 201phi2-1 Thomas et al., 2008 PG-binding domain (N)/unknown catalytic domain (C) Aeh1 Monod, C and Krisch, H. M. Aeh1p339 muraminidase (T4-like) YYZ-2008 Kropinski, A. M. YYZgp45 muraminidase (lambda-like)

Also preferred is the endolysin part deriving from endolysins of the Pseudomonas aeruginosa phages ΦKZ and EL, of the Pseudomonas putida phage OBP, of the phage LUZ24, or from T4 lysozyme, gp61 muramidase, PSP3 endolysin, of the Salmonella phage, of the Acinetobacter baumannii phage, of the E. coli Phage P2, of the E. coli phage N4 and K1F and of the Salmonella typhimurium phage.

Further preferred endolysins of the fusion protein are Listeria phage endolysins PlyA118, PlyA500, PlyPSA, PlyA511, PlyP35, PlyP40, Staphylococcal phage Phi 11 endolysin, Phi MR11 endolysin, LysK, Ply 2638, Clostridium perfringens PlyS6, Ply3626, Clostridium difficile: CD27L endolysin, Streptococcus: B30 endolysin, phage Dp-1 Pal amidase, C1 endolysin, Cpl-1 endolysin, PlyGBS, Enterococccus: PlyV12, Bacillus anthracis: Phage gamma endolysin PlyG, Propionibacterium phage endolysin PA6-gp20.

Preferred autolysins of the fusion protein are described in: Bacterial peptidoglycan (murein) hydrolases. Vollmer W, Joris B, Charlier P, Foster S. FEMS Microbiol Rev. 2008 March; 32(2):259-86. Epub 2008 Feb. 11. Review. An example of a preferred autolysin is the AtlA Autolysine.

Preferred bacteriocins are Lysostaphin (degrading Staphylococcus cell walls), Mutanolysin (degrading Streptococcus cell walls) and Enterolysin (degrading Enterococcus cell walls). More preferably, the bacteriocin of the fusion protein according to the present invention comprises an amino acid sequence according to SEQ ID NO: 87.

Further examples for the endolysin part of the fusion protein is selected from the group consisting of Cpl-1 according to SEQ ID NO: 84, Ply511 according to SEQ ID NO: 85, LysK according to SEQ ID NO: 86, PA6-gp20 according to SEQ ID NO: 88, phiKZgp144 according to SEQ ID NO: 1, ELgp188 according to SEQ ID NO: 2, Salmonella endolysin according to SEQ ID NO: 3, Enterobacteria phage T4 endolysin according to SEQ ID NO: 4, Acinetobacter baumannii endolysin according to SEQ ID NO: 5, E. coli Phage K1F endolysin according to SEQ ID NO: 6, OBPgpLYS according to SEQ ID NO: 7, PSP3 Salmonella endolysin (PSP3gp10) according to SEQ ID NO: 8, E. coli Phage P2 endolysin (P2gp09) according to SEQ ID NO: 9, Salmonella typhimurium phage muramidase STM0016 according to SEQ ID NO: 89, E. coli Phage N4 muramidase N4-gp61 according to SEQ ID NO: 90, N4-gp61 trunc. according to SEQ ID NO:91 and Ply 2638 according to SEQ ID NO: 92.

In another preferred embodiment of the present invention methods of eliminating, reducing or preventing bacterial biofilms by means of the fusion protein according to the present invention comprise modifications and/or alterations of the amino acid sequences. Such alterations and/or modifications may comprise mutations such as deletions, insertions and additions, substitutions or combinations thereof and/or chemical changes of the amino acid residues, e.g. biotinylation, acetylation, PEGylation, chemical changes of the amino-, SH- or carboxyl-groups. Said modified and/or altered endolysins exhibit the lytic activity of the respective wild type endolysin. However, said activity can be higher or lower as the activity of the respective wild type endolysin. Said activity can be about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or about 200% of the activity of the respective wild-type endolysin or even more. The activity can be measured by assays well known in the art by a person skilled in the art as e.g. the plate lysis assay or the liquid lysis assay which are e.g. described in Briers et al., J. Biochem. Biophys Methods 70: 531-533, (2007).

The peptide of the fusion protein according to the present invention may be linked to the enzyme, preferably to the endolysin, autolysin or bacteriocin by additional amino acid residues e.g. due to cloning reasons. Preferably, said additional amino acid residues may be not recognized and/or cleaved by proteases. Preferably said peptide may be linked to the enzyme by at least 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional amino acid residues. Preferably, the peptide fused on the N-terminus of the enzyme, preferably to the endolysin, autolysin or bacteriocin, of the fusion protein according to the invention further comprises additional amino acids on its N-terminus. Preferably the peptide comprises the amino acid methionine (Met), or methionine, glycine and serine (Met-Gly-Ser) or alanine, methionine and glycine (Ala-Met-Gly). In another preferred embodiment the peptide is linked to the N-terminus of the enzyme, preferably to the endolysin, autolysin or bacteriocin, by the additional amino acid residues, in particular glycine and serine (Gly-Ser). In another preferred embodiment the peptide is linked to the C-terminus of the enzyme by the additional amino acid residues, in particular glycine and serine (Gly-Ser).

In one aspect of the present invention the peptide with membrane and/or LPS disrupting activity comprises a positively charged peptide, which comprises one or more of the positively charged amino acids being lysine, arginine and/or histidine. Preferably, more than 80%, preferably more than 90%, preferably 100% of the amino acids in said peptide are positively charged amino acids. Advantageously, the cationic peptide is positioned at the N-terminal and/or the C-terminal end of the fusion protein, thus enhancing the cationicity of the latter proteins. In another embodiment of the invention, the cationic peptide fused to the enzyme, preferably to the endolysin, autolysin or bacteriocin is at least 5, more preferably at least 9 amino acids long.

In a preferred embodiment said peptide comprises about 3 to about 50, more preferably about 5 to about 20, for instance about 5 to about 15 amino acid residues and at least 20, 30, 40, 50, 60 or 70%, more preferably at least 80%, for instance at least 90% of the said amino acid residues are either arginine or lysine residues. In another preferred embodiment said peptide comprises about 3 to about 50, more preferably about 5 to about 20, for instance about 5 to about 15 amino acid residues and said amino acid residues are either arginine or lysine residues.

Preferably, the peptide of the fusion protein is fused to the N-terminus and/or to the C-terminus of the enzyme, preferably of the endolysin, autolysin or bacteriocin. In a particular preferred embodiment said peptide is only fused to the N-terminus of the enzyme, preferably the endolysin, autolysin or bacteriocin. However, also preferred are fusion proteins having a peptide both on the N-terminus and on the C-terminus. Said peptides on the N-terminus and on the C-terminus can be the same or distinct peptides.

The peptide of the fusion protein is preferably covalently bound to the enzyme. Preferably, said peptide consists of at least 5, more preferably at least of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or at least 100 amino acid residues. Especially preferred is a peptide comprising about 5 to about 100 amino acid residues, about 5 to about 50 or about 5 to about 30 amino acid residues. More preferred is a peptide comprising about 6 to about 42 amino acid residues, about 6 to about 39 amino acid residues, about 6 to about 38 amino acid residues, about 6 to about 31 amino acid residues, about 6 to about 25 amino acid residues, about 6 to about 24 amino acid residues, about 6 to about 22 amino acid residues, about 6 to about 21 amino acid residues, about 6 to about 20 amino acid residues, about 6 to about 19 amino acid residues, about 6 to about 16 amino acid residues, about 6 to about 14 amino acid residues, about 6 to about 12 amino acid residues, about 6 to about 10 amino acid residues or about 6 to about 9 amino acid residues.

In one aspect of the present invention the peptide is selected from the group of cationic peptides, polycationic peptides, hydrophobic peptides, antimicrobial peptides and amphiphatic peptides.

In one aspect of the present invention the peptide is a cationic and/or polycationic peptide, which comprises one or more of the positively charged amino acid residues of lysine, arginine and/or histidine, in particular of lysine and/or arginine. Preferably, more than about 20, 30, 40, 50, 60, 70, 75, 80, 85, 90, 95 or 99% of the amino acid residues in said peptide are positively charged amino acid residues, in particular lysine and/or arginine residues. Especially preferred are peptides consisting of about 100% positively charged amino acid residues, in particular arginine and/or lysine residues, wherein preferably about 60% to about 70% of said positively charged amino acid residues are lysine residues and about 30% to about 40% of said positively charged amino acid residues are arginine residues. More preferred is a peptide consisting of about 100% positively charged amino acid residues, in particular arginine and/or lysine residues, wherein preferably about 64% to about 68% of said positively charged amino acid residues are lysine and about 32% to about 36% of said positively charged amino acid residues are arginine. Peptides consisting of either only arginine or only lysine are also preferred.

Especially preferred are cationic and/or polycationic peptides of the fusion protein comprising at least one motive according to SEQ ID NO: 10 (KRKKRK). In particular cationic peptides comprising at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17 motives according to SEQ ID NO: 10 (KRKKRK) are preferred. More preferred are cationic peptides comprising at least one KRK motive (lys-arg-lys), preferable at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32 or 33 KRK motives.

In another preferred embodiment of the present invention the peptide is a cationic peptide comprising beside the positively charged amino acid residues, in particular lysine and/or arginine residues, neutrally charged amino acid residues, in particular glycine and/or serine residues. Preferred are cationic peptides consisting of about 70% to about 100%, or about 80% to about 95%, or about 85% to about 90% positively charged amino acid residues, in particular lysine, arginine and/or histidine residues, more preferably lysine and/or arginine residues and of about 0% to about 30%, or about 5% to about 20%, or about 10% to about 20% neutrally charged amino acid residues, in particular glycine and/or serine residues. Preferred are peptides consisting of about 4% to about 8% serine residues, of about 33% to about 36% arginine residues and of about 56% to about 63% lysine residues. Especially preferred are peptides comprising at least one motive according to SEQ ID NO: 32 (KRXKR), wherein X is any other amino acid than lysine, arginine and histidine. Especially preferred are peptides comprising at least one motive according to SEQ ID NO: 33 (KRSKR). More preferred are cationic peptides comprising at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or about 20 motives according to SEQ ID NO: 32 (KRXKR) or SEQ ID NO: 33 (KRSKR).

Also preferred are peptides of the fusion protein consisting of about 9 to about 16% glycine residues, of about 4 to about 11% serine residues, of about 26 to about 32% arginine residues and of about 47 to about 55% lysine residues. Especially preferred are peptides comprising at least one motive according to SEQ ID NO: 34 (KRGSG). More preferred are cationic peptides comprising at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or about 20 motives according to SEQ ID NO: 34 (KRGSG).

In another preferred embodiment of the present invention the cationic peptide comprises beside the positively charged amino acid residues, in particular lysine and/or arginine residues, hydrophobic amino acid residues, in particular valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues. Preferred are cationic peptides of the fusion protein consisting of about 70% to about 100%, or about 80% to about 95%, or about 85% to about 90% positively charged amino acid residues, in particular lysine and/or arginine residues and of about 0% to about 30%, or about 5% to about 20%, or about 10% to about 20% hydrophobic amino acid residues, valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues.

Especially preferred are peptides of the fusion protein selected from the group consisting of the following sequences presented in Table 2.

TABLE 2 Peptide length SEQ ID NO: KRKKRK 6 SEQ ID NO: 10 KRKKRKKRK 9 SEQ ID NO: 11 RRRRRRRRR 9 SEQ ID NO: 12 KKKKKKKK 8 SEQ ID NO: 13 KRKKRKKRKK 10 SEQ ID NO: 14 KRKKRKKRKKRK 12 SEQ ID NO: 15 KRKKRKKRKKRKKR 14 SEQ ID NO: 16 KKKKKKKKKKKKKKKK 16 SEQ ID NO: 17 KRKKRKKRKKRKKRKKRKK 19 SEQ ID NO: 18 RRRRRRRRRRRRRRRRRRR 19 SEQ ID NO: 19 KKKKKKKKKKKKKKKKKKK 19 SEQ ID NO: 20 KRKKRKKRKRSKRKKRKKRK 20 SEQ ID NO: 21 KRKKRKKRKRSKRKKRKKRKK 21 SEQ ID NO: 22 KRKKRKKRKKRKKRKKRKKRK 21 SEQ ID NO: 23 KRKKRKKRKRGSGKRKKRKKRK 22 SEQ ID NO: 24 KRKKRKKRKRGSGSGKRKKRKKRK 24 SEQ ID NO: 25 KRKKRKKRKKRKKRKKRKKRKKRKK 25 SEQ ID NO: 26 KRKKRKKRKRSKRKKRKKRKRSKRKKRKKRK 31 SEQ ID NO: 27 KRKKRKKRKRGSGSGKRKKRKKRKGSGSGKRKKRKKRK 38 SEQ ID NO: 28 KRKKRKKRKKRKKRKKRKKRKKRKKRKKRKKRKKRKKRK 39 SEQ ID NO: 29 KRKKRKKRKRSKRKKRKKRKRSKRKKRKKRKRSKRKKRKKRK 42 SEQ ID NO: 30

Preferably, the peptide of the fusion protein is no tag such as a His-tag, Strep-tag, Avi-tag, Myc-tag, Gst-tag, JS-tag, cystein-tag, FLAG-tag or other tags known in the art and no thioredoxin or maltose binding proteins (MBP). However, the fusion protein according to the present invention may comprise in addition such tag or tags.

Preferably, the peptide of the fusion protein has the function to lead the fusion protein according to the present invention through the outer membrane of bacteria but has no or only low activity when administered without being fused to the endolysin, autolysin or bacteriocin. The function to lead the fusion protein through the outer membrane of Gram-negative and/or Gram-positive bacteria is caused by the potential of the outer membrane or LPS disrupting or permeabilising or destabilizing activity of said peptide. Such outer membrane or LPS disrupting or permeabilising or destabilizing activity of the peptide may be determined in a method as follows: The bacteria cells to be treated are cultured in liquid medium or on agar plates. Then the bacteria cell concentration in the liquid medium is determined photometrically at OD600nm or the colonies on the agar plates are counted, respectively. Now, the bacteria cells in liquid medium or on the plates are treated with a fusion protein according to the invention. After incubation the bacteria cell concentration in the liquid medium is determined photometrically at OD600nm or the colonies on the agar plates are counted again. If the fusion protein exhibits such outer membrane or LPS disrupting or permeabilising or destabilizing activity, the bacteria cells are lysed due to the treatment with the fusion protein and thus, the bacteria cell concentration in the liquid medium or the number of the bacteria colonies on the agar plate is reduced. Thus, the reduction in bacteria cell concentration or in the number of bacteria colonies after treatment with fusion protein is indicative for an outer membrane or LPS disrupting or permeabilising or destabilizing activity of the fusion protein.

In a further embodiment of the present invention the peptide is an antimicrobial peptide comprising a positive net charge and around 50% hydrophobic amino acids. The antimicrobial peptides are amphiphatic, with a length of about 12 to about 50 amino acid residues. The antimicrobial peptides are naturally occurring in insects, fish, plants, arachnids, vertebrates or mammals. Preferably the antimicrobial peptide may be naturally occurring in radish, silk moth, wolf spider, frog, preferably in Xenopus laevis, Rana frogs, more preferably in Rana catesbeiana, toad, preferably Asian toad Bufo bufo gargarizans, fly, preferably in Drosophila, more preferably in Drosophila melanogaster, in Aedes aegypti, in honey bee, bumblebee, preferably in Bombus pascuorum, flesh fly, preferably in Sarcophaga peregrine, scorpion, horseshoe crab, catfish, preferably in Parasilurus asotus, cow, pig, sheep, porcine, bovine, monkey and human.

In another preferred embodiment the antimicrobial peptide of the fusion protein consists of about 0% to about 5%, or about 0% to about 35%, or about 10% to about 35% or about 15% to about 45%, or about 20% to about 45% positively charged amino acid residues, in particular lysine and/or arginine residues and of about 50% to about 80%, or about 60% to about 80%, or about 55% to about 75%, or about 70% to about 90% hydrophobic amino acid residues, valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues.

In another preferred embodiment of the present invention the antimicrobial peptide of the fusion protein consists of about 4% to about 58% positively charged amino acid residues, in particular lysine and/or arginine residues and of about 33% to about 89% hydrophobic amino acid residues, valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues. Examples for antimicrobial peptides of the fusion protein according to the present invention are listed in the following table.

TABLE 3 Peptide Amino acid sequence SEQ ID NO LL-37 LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVP SEQ ID NO: 93 RTES SMAP-29 RGLRRLGRKIAHGVKKYGPTVLRIIRIAG SEQ ID NO: 94 Indolicidin ILPWKWPWWPWRR SEQ ID NO: 95 Protegrin RGGRLCYCRRRFCVCVGR SEQ ID NO: 96 Cecropin P1 SWLSKTAKKLENSAKKRISEGIAIAIQGGPR SEQ ID NO: 97 Magainin GIGKFLHSAKKFGKAFVGEIMNS SEQ ID NO: 98 Pleurocidin GWGSFFKKAAHVGKHVGKAALTHYL SEQ ID NO: 99 Cecropin A GGLKKLGKKLEGAGKRVFNAAEKALPVVAG SEQ ID NO: 100 (A. aegypti) AKALRK Cecropin A (D. GWLKKIGKKIERVGQHTRDATIQGLGIPQQAA SEQ ID NO: 101 melanogaster) NVAATARG Buforin II TRSSRAGLQFPVGRVHRLLRK SEQ ID NO: 102 Sarcotoxin IA GWLKKIGKKIERVGQHTRDATIQGLGIAQQAA SEQ ID NO: 103 NVAATAR Apidaecin ANRPVYIPPPRPPHPRL SEQ ID NO: 104 Ascaphine 5 GIKDWIKGAAKKLIKTVASHIANQ SEQ ID NO: 105 Nigrocine 2 GLLSKVLGVGKKVLCGVSGLVC SEQ ID NO: 106 Pseudin 1 GLNTLKKVFQGLHEAIKLINNHVQ SEQ ID NO: 107 Ranalexin FLGGLIVPAMICAVTKKC SEQ ID NO: 108 Melittin GIGAVLKVLTTGLPALISWIKRKRQQ SEQ ID NO: 109 Lycotoxin 1 IWLTALKFLGKHAAKKLAKQQLSKL SEQ ID NO: 110 Parasin 1 KGRGKQGGKVRAKAKTRSS SEQ ID NO: 111 Buforin I AGRGKQGGKVRAKAKTRSSRAGLQFPVGRVH SEQ ID NO: 112 RLLRKGNY Dermaseptin 1 ALWKTMLKKLGTMALHAGKAALGAAADTIS SEQ ID NO: 113 QGTQ Bactenecin 1 RLCRIVVIRVCR SEQ ID NO: 114 Thanatin GSKKPVPIIYCNRRTGKCQRM SEQ ID NO: 115 Brevinin 1T VNPIILGVLPKVCLITKKC SEQ ID NO: 116 Ranateurin 1 SMLSVLKNLGKVGLGFVACKINIKQC SEQ ID NO: 117 Esculentin 1 GIFSKLGRKKIKNLLISGLKNVGKEVGMDVVR SEQ ID NO: 118 TGIKIAGCKIKGEC Tachyplesin RWCFRVCYRGICYRKCR SEQ ID NO: 119 Androctonin RSVCRQIKICRRRGGCYYKCTNRPY SEQ ID NO: 120 alpha-defensin DCYCRIPACIAGERRYGTCIYQGRLWAFCC SEQ ID NO: 121 beta-defensin NPVSCVRNKGICVPIRCPGSMKQIGTCVGRAV SEQ ID NO: 122 KCCRKK theta-defensin GFCRCLCRRGVCRCICTR SEQ ID NO: 123 defensin ATCDLLSGTGINHSACAAHCLLRGNRGGYCN SEQ ID NO: 124 (sapecin A) GKAVCVCRN Thionin TTCCPSIVARSNFNVCRIPGTPEAICATYTGCIII SEQ ID NO: 125 (crambin) PGATCPGDYAN defensin from QKLCQRPSGTWSGVCGNNNACKNQCIRLEKA SEQ ID NO: 126 radish RHGSCNYVFPAHCICYFPC Drosomycin DCLSGRYKGPCAVWDNETCRRVCKEEGRSSG SEQ ID NO: 127 HCSPSLKCWCEGC Hepcidin DTHFPICIFCCGCCHRSKCGMCCKT SEQ ID NO: 128 Bac 5 RFRPPIRRPPIRPPFYPPFRPPIRPPIFPPIRPPFRPP SEQ ID NO: 129 LGRPFP PR 39 RRRPRPPYLPRPRPPPFFPPRLPPRIPPGFPPRFPP SEQ ID NO: 130 RFP Pyrrhocoricin VDKGSYLPRPTPPRPIYNRN SEQ ID NO: 131 Histatin 5 DSHAKRHHGYKRKFHEKHHSHRGY SEQ ID NO: 132

In a further embodiment of the present invention the peptide is a sushi peptide which is described by Ding J L, Li P, Ho B Cell Mol Life Sci. 2008 April; 65(7-8):1202-19. The Sushi peptides: structural characterization and mode of action against Gram-negative bacteria. Especially preferred is the sushi 1 peptide according to SEQ ID NO: 133.

Preferred sushi peptides of the fusion protein are sushi peptides Sib 1 and Sib 3 and multiples thereof; FASEB J. 2000 September ; 14(12):1801-13.

In a further embodiment of the present invention the peptide is a hydrophobic peptide, which comprises at least 90% of the hydrophobic amino acid residues of valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and/or glycine. In another preferred embodiment the hydrophobic peptide of the fusion protein consist of about 90% to about 95%, or of about 90 to about 100%, or of about 95% to about 100% of the hydrophobic amino acid residues of valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and/or glycine.

Preferred hydrophobic peptides of the fusion protein are Walmagh1 having the amino acid sequence according to SEQ ID NO: 134 and the hydrophobic peptide of the fusion protein having the amino acid sequence Phe-Phe-Val-Ala-Pro (SEQ ID NO: 135).

In a further embodiment of the present invention the peptide is an amphiphatic peptide, which comprises one or more of the positively charged amino acid residues of lysine, arginine and/or histidine, combined to one or more of the hydrophobic amino acid residues of valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and/or glycine. Side chains of the amino acid residues are oriented in order that cationic and hydrophobic surfaces are clustered at opposite sides of the peptide. Preferably, more than about 30, 40, 50, 60 or 70% of the amino acids in said peptide are positively charged amino acids. Preferably, more than about 30, 40, 50, 60 or 70%, of the amino acid residues in said peptide are hydrophobic amino acid residues. Advantageously, the amphiphatic peptide is fused at the N-terminal and/or the C-terminal end of the enzyme having cell wall degrading activity, thus enhancing the amphiphaticity of the latter proteins.

In another embodiment of the present invention the peptide is an amphiphatic peptide consisting of at least 5, more preferably at least of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 amino acid residues. In a preferred embodiment at least about 30, 40, 50, 60 or 70% of the said amino acid residues of the amphiphatic peptide are either arginine or lysine residues and/or at least about 30, 40, 50, 60 or 70% of the said amino acid residues of the amphiphatic peptide are of the hydrophobic amino acids valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and/or glycine.

In another preferred embodiment of the present invention the peptide is an amphiphatic peptide comprising beside the positively charged amino acid residues, in particular lysine and/or arginine residues, hydrophobic amino acid residues, in particular valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues. Preferred are amphiphatic peptides consisting of about 10% to about 50%, or about 20% to about 50%, or about 30% to about 45% or about 5% to about 30% positively charged amino acid residues, in particular lysine and/or arginine residues and of about 50% to about 85%, or about 50% to about 90%, or about 55% to about 90%, or about 60% to about 90%, or about 65% to about 90% hydrophobic amino acid residues, valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues. In another preferred embodiment amphiphatic peptides consisting of 12% to about 50% positively charged amino acid residues, in particular lysine and/or arginine residues and of about 50% to about 85% hydrophobic amino acid residues, valine, isoleucine, leucine, methionine, phenylalanine, tryptophan, cysteine, alanine, tyrosine, histidine, threonin, serine, proline and glycine residues, more preferably alanine, valine, leucine, isoleucine, phenylalanine, and/or tryptophan residues.

Preferred amphiphatic peptides of the fusion protein are, α4-helix of T4 lysozyme according to SEQ ID NO: 136 and WLBU2-Variant having the amino acid sequence according to SEQ ID NO: 137 and Walmagh 2 according to SEQ ID NO: 138.

In a preferred embodiment of the present invention the fusion protein consists of a peptide according to SEQ ID NO: 10 to 30, 32 to 34 and 93 to 138 and an endolysin according to SEQ ID NO: 1 to 9, 84 to 86 and 88 to 92 or a bacteriocin according to SEQ ID NO: 87. In a preferred embodiment the fusion protein comprises a peptide selected from the group of peptides according to SEQ ID NO: 10 to 30, 32 to 34 and 93 to 138 and an endolysin selected from the group of endolysins according to SEQ ID NO: 1 to 9, 84 to 86 and 88 to 92 or a bacteriocin according to SEQ ID NO: 87.

Especially preferred are fusion proteins selected from the group consisting of the following fusion proteins presented in the Table 4.

TABLE 4 SEQ ID NO: Peptide (fusion Endolysin/Bacteriocin (N-terminal unless Fusion protein protein) part otherwise indicated) POLY-gp144 SEQ ID NO: 35 SEQ ID NO: 1 SEQ ID NO: 11 (POLY)²-gp144 SEQ ID NO: 36 SEQ ID NO: 1 SEQ ID NO: 21 (POLY)³-gp144 SEQ ID NO: 37 SEQ ID NO: 1 SEQ ID NO: 27 (POLY)⁴-gp144 SEQ ID NO: 38 SEQ ID NO: 1 SEQ ID NO: 30 POLY-gp188 SEQ ID NO: 39 SEQ ID NO: 2 SEQ ID NO: 11 (POLY)²-gp188 SEQ ID NO: 40 SEQ ID NO: 2 SEQ ID NO: 21 (POLY)³-gp188 SEQ ID NO: 41 SEQ ID NO: 2 SEQ ID NO: 27 (POLY)⁴-gp188 SEQ ID NO: 42 SEQ ID NO: 2 SEQ ID NO: 30 pKKZ144pET32b SEQ ID NO: 43 SEQ ID NO: 1 SEQ ID NO: 14 KRK_6_pET32b SEQ ID NO: 44 SEQ ID NO: 1 SEQ ID NO: 10 KRK_12_pET32b SEQ ID NO: 45 SEQ ID NO: 1 SEQ ID NO: 15 KRK_14_pET32b SEQ ID NO: 46 SEQ ID NO: 1 SEQ ID NO: 16 R9_pET32b SEQ ID NO: 47 SEQ ID NO: 1 SEQ ID NO: 12 K8_pET32b SEQ ID NO: 48 SEQ ID NO: 1 SEQ ID NO: 13 pK2KZ144_pET32b_mod3 SEQ ID NO: 49 SEQ ID NO: 1 SEQ ID NO: 28 PKPSP3gp10 SEQ ID NO: 53 SEQ ID NO: 8 SEQ ID NO: 11 PKP2gp09 SEQ ID NO: 57 SEQ ID NO: 9 SEQ ID NO: 11 PKOBPgpLYS SEQ ID NO: 61 SEQ ID NO: 7 SEQ ID NO: 11 pK2KZ144pET32b SEQ ID NO: 62 SEQ ID NO: 1 SEQ ID NO: 22 pK3KZ144pET32b SEQ ID NO: 63 SEQ ID NO: 1 SEQ ID NO: 27 pK4KZ144pET32b SEQ ID NO: 64 SEQ ID NO: 1 SEQ ID NO: 30 KRK_19_pET32b SEQ ID NO: 66 SEQ ID NO: 1 SEQ ID NO: 18 KRK_21_pET32b SEQ ID NO: 67 SEQ ID NO: 1 SEQ ID NO: 23 KRK_25_pET32b SEQ ID NO: 68 SEQ ID NO: 1 SEQ ID NO: 26 KRK_39_pET32b SEQ ID NO: 69 SEQ ID NO: 1 SEQ ID NO: 29 K19_pET32b SEQ ID NO: 70 SEQ ID NO: 1 SEQ ID NO: 20 K16_pET32b SEQ ID NO: 71 SEQ ID NO: 1 SEQ ID NO: 17 pKKZ-144_K2_pET32b SEQ ID NO: 72 SEQ ID NO: 1 N-terminal: SEQ ID NO: 11 C-terminal: SEQ ID NO: 21 pK2KZ144_pET32b_mod1 SEQ ID NO: 73 SEQ ID NO: 1 SEQ ID NO: 24 pK2KZ144_pET32b_mod2 SEQ ID NO: 74 SEQ ID NO: 1 SEQ ID NO: 25 smi01_KRK9 SEQ ID NO: 75 SEQ ID NO: 5 SEQ ID NO: 11 smi02_KRK9 SEQ ID NO: 76 SEQ ID NO: 4 SEQ ID NO: 11 smi03_KRK9 SEQ ID NO: 77 SEQ ID NO: 6 SEQ ID NO: 11 smi04_KRK9 SEQ ID NO: 78 SEQ ID NO: 3 SEQ ID NO: 11 SMAP-29-KZ144 SEQ ID NO: SEQ ID NO: 1 SEQ ID NO: 94 139 Ply2638-PK SEQ ID NO: SEQ ID NO: 92 SEQ ID NO: 11 140 Pentapeptid-Ply511 SEQ ID NO: SEQ ID NO: 85 SEQ ID NO: 135 141 PK-Lysostaphin SEQ ID NO: SEQ ID NO: 87 SEQ ID NO: 11 142

The fusion proteins according to the present invention, and thus in particular the especially preferred fusion proteins according to SEQ ID NO: 35 to 49, 53, 57, 61 to 64, 66 to 78 and 139 to 142 may additional comprise a methionine on the N-terminus.

The fusion proteins according to the present invention, and thus in particular the especially preferred fusion proteins according to SEQ ID NO: 35 to 49, 53, 57, 61 to 64, 66 to 78 and 139 to 142 may additional comprise a tag e.g. for purification. Preferred is a His₆-tag, preferably at the C-terminus of the fusion protein. Said tag can be linked to the fusion protein by additional amino acid residues e.g. due to cloning reasons. Preferably said tag can be linked to the fusion protein by at least 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional amino acid residues. In a preferred embodiment the fusion protein comprises a His₆-tag at its C-terminus linked to the fusion protein by the additional amino acid residues lysine and glycine (Lys-Gly) or leucine and glutamic acid (Leu-Glu). Preferably, said additional amino acid residues may be not recognized or cleaved by proteases. In another preferred embodiment the fusion protein comprises a His₆-tag at its N-terminus linked to the fusion protein by the additional amino acid residues lysine and glycine (Lys-Gly) or leucine and glutamic acid (Leu-Glu). In another preferred embodiment the fusion protein comprises a His₆-tag at its N- and C-terminus linked to the enzyme, preferably to the endolysin, autolysin or bacteriocin by the additional amino acid residues lysine and glycine (Lys-Gly) or leucine and glutamic acid (Leu-Glu).

In particular, the fusion proteins as used in the examples as described below are preferred. The fusion proteins according to SEQ ID NO: 35 to 42, 53, 57 and 61 as used in the examples comprise a His₆-tag at the C-terminus linked to the fusion protein by the additional amino acid residues lysine and glycine (Lys-Gly). The fusion protein according to SEQ ID NO: 43 to 49, 75, 139, 141 and 142 as used in the examples comprise a His₆-tag at the C-terminus linked to the respective fusion protein by the additional amino acid residues leucine and glutamic acid (Leu-Glu).

Fusion proteins are constructed by linking at least two nucleic acid sequences using standard cloning techniques as described e.g. by Sambrook et al. 2001, Molecular Cloning: A Laboratory Manual. Such a protein may be produced, e.g., in recombinant DNA expression systems. Such fusion proteins according to the present invention can be obtained by fusing the nucleic acids for endolysin, autolysin or bacteriocin and the respective peptide.

As some fusion proteins may either be toxic upon expression in bacteria, or not homogenous due to protein degradation, the strategy might be to express these fusion proteins fused or linked to other additional proteins. Example for these other additional protein is Thioredoxin, which was shown to mediate expression of toxic antimicrobial peptides in E. coli (TrxA mediating fusion expression of antimicrobial peptide CM4 from multiple joined genes in Escherichia coli. Zhou L, Zhao Z, Li B, Cai Y, Zhang S. Protein Expr Purif. 2009 April; 64(2):225-230).

For antimicrobial function of the fusion proteins it may be necessary to remove the additional fusion protein by proteolytic cleavage. Commercially available kits like the pET32 expression system (Novagen), may need to modify e.g. the N-terminus of the fusion depending on the protease used, like from MGS to AMGS (SEQ ID NO: 31), were the remaining alanine residue results from an introduced Enterokinase cleavage site.

In another preferred embodiment of the present invention the peptides of the fusion proteins according to the present invention comprise modifications and/or alterations of the amino acid sequences. Such alterations and/or modifications may comprise mutations such as deletions, insertions and additions, substitutions or combinations thereof and/or chemical changes of the amino acid residues, e.g. biotinylation, acetylation, PEGylation, chemical changes of the amino-, SH- or carboxyl-groups.

The present invention further relates to methods of eliminating, reducing or preventing bacterial biofilms by means of an isolated nucleic acid molecule encoding the fusion protein according to the present invention. The present invention further relates to a vector comprising the nucleic acid molecule according to the present invention. Said vector may provide for the constitutive or inducible expression of said fusion protein according to the present invention.

The fusion proteins may be obtained from a micro-organism, such as a genetically modified suitable host cell which expresses said fusion proteins. Said host cell may be a micro-organism such as bacteria or yeast or fungi or an animal cell as e.g. a mammalian cell, in particular a human cell. In one embodiment of the present invention the yeast cell is a Pichia pastoris cell. The host may be selected due to mere biotechnological reasons, e.g. yield, solubility, costs, etc. but may be also selected from a medical point of view, e.g. a non-pathological bacteria or yeast, human cells.

In a further aspect the present invention relates to methods of eliminating, reducing or preventing bacterial biofilms by means of a composition, preferably a pharmaceutical composition, comprising a fusion protein according to the present invention and/or a host transformed with a nucleic acid molecule or a vector comprising a nucleotide sequence encoding a fusion protein according to the present invention.

In a preferred embodiment of the present invention the methods of eliminating, reducing or preventing bacterial biofilms by means of the composition comprises additionally agents permeabilizing the outer membrane of Gram-negative bacteria such metal chelators as e.g. EDTA, TRIS, lactic acid, lactoferrin, polymyxin, citric acid and/or other substances as described e.g. by Vaara (Agents that increase the permeability of the outer membrane. Vaara M. Microbiol Rev. 1992 September; 56(3):395-441). Also preferred are compositions comprising combinations of the above mentioned permeabilizing agents. Especially preferred is a composition comprising about 10 μM to about 100 mM EDTA, more preferably about 50 μM to about 10 mM EDTA, more preferably about 0.5 mM to about 10 mM EDTA, more preferably about 0.5 mM to about 2 mM EDTA, more preferably about 0.5 mM to 1 mM EDTA. However, also compositions comprising about 10 μM to about 0.5 mM EDTA are preferred. Also preferred is a composition comprising about 0.5 mM to about 2 mM EDTA, more preferably about 1 mM EDTA and additionally about 10 to about 100 mM TRIS.

The present invention also relates to methods of eliminating, reducing or preventing bacterial biofilms by means of a fusion protein according to the present invention and/or a host transformed with a nucleic acid comprising a nucleotide sequence encoding a fusion protein according to the present invention for use as a medicament.

In a further aspect the present invention relates to the use of a fusion protein according to the present invention and/or a host transformed with a vector comprising a nucleic acid molecule comprising a nucleotide sequence encoding a fusion protein according to the present invention for eliminating, reducing and preventing bacterial biofilms. Preferred is the use wherein the bacteria generating the biofilm cause a disorder, disease or condition detrimental to plants, animals and/or human beings. Preferred is the use wherein the bacteria generating the biofilm may be Gram-negative bacteria of bacterial groups, families, genera or species comprising strains pathogenic for humans or animals like Enterobacteriaceae (Escherichia, especially E. coli, Salmonella, Shigella, Citrobacter, Edwardsiella, Enterobacter, Hafnia, Klebsiella, especially K. pneumoniae, Morganella, Proteus, Providencia, Serratia, Yersinia), Pseudomonadaceae (Pseudomonas, especially P. aeruginosa, Burkholderia, Stenotrophomonas, Shewanella, Sphingomonas, Comamonas), Neisseria, Moraxella, Vibrio, Aeromonas, Brucella, Francisella, Bordetella, Legionella, Bartonella, Coxiella, Haemophilus, Pasteurella, Mannheimia, Actinobacillus, Gardnerella, Spirochaetaceae (Treponema and Borrelia), Leptospiraceae, Campylobacter, Helicobacter, Spirillum, Streptobacillus, Bacteroidaceae (Bacteroides, Fusobacterium, Prevotella, Porphyromonas), Acinetobacter, especially A. baumannii. Preferably, said disorder, disease or condition may be caused by Pseudomonas, in particular Pseudomonas aeruginosa and/or Pseudomonas putida, Burkholderia, in particular Burkholderia pseudomallei and/or Burkholderia solanacearum, Salmonella, in particular Salmonella typhimurium and/or Salmonella Enteritidis, Acinetobacter, in particular Acinetobacter baumannii, Escherichia coli and/or Klebsiella, in particular Klebsiella pneumoniae. In particular the treatment and/or prevention of the disorder, disease or condition may be caused by Gram-positive bacteria of bacterial groups, families, genera or species comprising strains pathogenic for humans or animals like Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus mutans, Streptococcus equi, Clostridium difficile, Clostridium botulinum, Clostridium tetani, Clostridium perfringens, Bacillus anthracis, Bacillus cereus, Propionibacterium acnes, Mycobacterium avium, Mycobacterium tuberculosis, Corynebacterium diphteriae, Mycoplasma pneumoniae, Actinomyces.

In a preferred embodiment, the fusion protein, preferably the endolysin variant, autolysin variant or bacteriocin variant

In a further aspect the present invention relates to a method of treating a disorder, disease or condition associated with bacterial biofilm in a subject in need of treatment and/or prevention, which method comprises administering to said subject an effective amount of a fusion protein according to the present invention and/or an effective amount of a host transformed with a nucleic acid comprising a nucleotide sequence encoding a fusion protein according to the present invention or a composition according to the present invention. The subject may be a human or an animal.

Preferably said method of treatment may be for the treatment and/or prevention of infections caused by Gram-negative and/or Gram-positive bacteria associated with bacterial biofilm, in particular by the Gram-negative and Gram-positive bacteria as listed above. In particular said method of treatment may be for the treatment and/or prevention of infections of the skin, of soft tissues, the respiratory system, the lung, the digestive tract, the eye, the ear, the teeth, the nasopharynx, the mouth, the bones, the vagina, of wounds of bacteraemia and/or endocarditis caused by Gram-negative and/or Gram-positive bacteria associated with bacterial biofilm, in particular by the Gram-negative and Gram-positive bacteria as listed above.

The dosage and route of administration used in a method of treatment or prophylaxis according to the present invention depends on the specific disease/site of infection to be treated. The route of administration may be for example oral, topical, nasopharyngeal, parenteral, inhalational, intravenous, intramuscular, intrathecal, intraspinal, endobronchial, intrapulmonal, intraosseous, intracardial, intraarticular, rectal, vaginal or any other route of administration. In a preferred embodiment the fusion protein is applied topical to the biological material, preferably the skin, in particular of mammals, preferably of human. In a preferred embodiment the fusion protein is applied systemic to the biological material, preferably the blood, in particular of mammals, preferably of human.

For application of a fusion protein according to the present invention and/or an effective amount of a host transformed with a nucleic acid comprising a nucleotide sequence encoding a fusion protein according to the present invention or a composition according to the present invention to a site of infection (or site endangered to be infected) a formulation may be used that protects the active compounds from environmental influences such as proteases, oxidation, immune response etc., until it reaches the site of infection. Therefore, the formulation may be capsule, dragee, pill, powder, suppository, emulsion, suspension, gel, lotion, cream, salve, injectable solution, syrup, spray, inhalant or any other medical reasonable galenic formulation. Preferably, the galenic formulation may comprise suitable carriers, stabilizers, flavourings, buffers or other suitable reagents. For example, for topical application the formulation may be a lotion, cream, gel, salve or plaster, for nasopharyngeal application the formulation may be saline solution to be applied via a spray to the nose. For oral administration in case of the treatment and/or prevention of a specific infection site e.g. in the intestine, it can be necessary to protect a fusion protein according to the present invention from the harsh digestive environment of the gastrointestinal tract until the site of infection is reached. Thus, bacteria as carrier, which survive the initial steps of digestion in the stomach and which secret later on a fusion protein according to the present invention into the intestinal environment can be used.

In a specific embodiment the present invention relates to the use of a fusion protein according to the present invention and/or a host transformed with a vector comprising a nucleic acid molecule comprising a nucleotide sequence encoding a fusion protein according to the present invention in the manufacture of a medicament for the treatment and/or prevention of a disorder, disease or condition caused by Gram-negative and/or Gram-positive bacterial infections associated with bacterial biofilm. A preferred embodiment relates to the use of a fusion protein according to the present invention in the manufacture of a medicament for the treatment and/or prevention of a disorder, disease or condition caused by Gram-negative and/or Gram-positive bacterial infections associated with bacterial biofilm in combination or addition to antibiotics.

In a specific embodiment the present invention relates to the use of a fusion protein according to the present invention and/or a host transformed with a vector comprising a nucleic acid molecule comprising a nucleotide sequence encoding a fusion protein according to the present invention in the manufacture of a medicament for the treatment and/or prevention of a disorder, disease or condition caused by Pseudomonas associated with bacterial biofilm, particularly by Pseudomonas aeruginosa in particular intestinal affections, in particular in infants, infections of the meninges, e.g. meningitis haemorrhagica, infections of the middle ear, the skin (Eethyma gangraenosum), in particular burns, the urinary tract, rhinitis, bacteremic pneumonia, in particular wherein the patient is suffering from cystic fibrosis or hematologic malignancies such as leukemia, or with neutropenia from immunosuppressive therapy, septicemia, in particular because of long-term intravenous or urinary catheterization, invasive surgical procedures and severe burns, endocarditis, in particular wherein the patient is a intravenous drug user or a patient with complications from open heart surgery, highly destructive ocular infections, in particular after the use of contaminated ophthalmologic solutions or severe facial burns, osteochondritis, in particular as a result of severe trauma or puncture wounds through contaminated clothing.

In another specific embodiment of the present invention the disorder, disease or condition is caused by Burkholderia pseudomallei associated with bacterial biofilm, in particular Whitmore's Disease, chronic pneumonia, septicemia, in particular wherein the patient has a traumatized skin lesion. In another specific embodiment of the present invention the disorder, disease or condition is caused by Salmonella thyphimurium and Salmonella enteritidis associated with bacterial biofilm, in particular acute gastroenteritis and local purulent processes, particularly osteomyelitis, endocarditis, cholecystitis and especially caused by Salmonella thyphimurium meningitis, in particular wherein the patient is less than two years old. In another specific embodiment of the present invention the disorder, disease or condition is caused by Salmonella typhi, in particular typus. In another specific embodiment of the present invention the disorder, disease or condition is caused by Salmonell paratyphi, in particular paratyphus. In another specific embodiment of the present invention the disorder, disease or condition is caused by Acinetobacter baumannii associated with bacterial biofilm, in particular bronchitis, pneumonia, wound infections and septicemia, in particular as a result of intravenous catheterization. In another specific embodiment of the present invention the disorder, disease or condition is caused by Escherichia coli associated with bacterial biofilm, in particular extra intestinal infections, particularly appendicitis, purulent cholecystitis, peritonitis, purulent meningitis and infection of the urinary tract, intraintestinal E. coli infections, particularly epidemic enteritis, and infectious disease similar to dysentery, septicemia, enterotoxemia, mastitis and dysentery. In another specific embodiment of the present invention the disorder, disease or condition is caused by Klebsiella pneumoniae associated with bacterial biofilm, in particular pneumonia, bacteremia, meningitis and infections of the urinary tract. In a specific embodiment the present invention relates to the use of a fusion protein according to the present invention and/or a host transformed with a vector comprising a nucleic acid molecule comprising a nucleotide sequence encoding a fusion protein according to the present invention in the manufacture of a medicament for the treatment and/or prevention of a disorder, disease or condition caused by Listeria monocytogenes, in particular Granulomatosis infantiseptica (listeriosis of newborns), mononucleosis, conjunctivitis, meningitis, granulomatosis septica and the listeriosis of pregnant women. In another specific embodiment of the present invention the disorder, disease or condition is caused by Staphylococcus aureus, in particular infections of the skin like pyoderma, particularly folliculitis, furuncle, carbuncle, abscesses of the sweat glands and pemphigus, and like scaled skin syndrome. The scaled skin syndrome can appear in three clinical pictures: dermatitis exfoliativa, impetigo bullosa and scarlatiniform erythroderma. Moreover the disorder, disease or condition caused by Staphylococcus aureus is Staphylococcus pneumonia, hospitalism, in particular surgical wound infections, mastitis puerperalis and enterokolitis, and food poisonings. In another specific embodiment of the present invention the disorder, disease or condition is caused by Streptococcus pyogenes, in particular tonsillitis, pharyngitis, scarlet, erysipelas, rheumatic fever and acute glomerulonephritis. In another specific embodiment of the present invention the disorder, disease or condition is caused by Streptococcus pneumoniae, in particular pneumonia, ulcus serpens corneae, otitis media, meningitis, peritonitis, mastoiditis and osteomyelitis.

In another specific embodiment of the present invention the disorder, disease or condition is caused by Clostridium perfringens, in particular gas gangrene, enteritis necroticans ulcerosa and food poisonings. In another specific embodiment of the present invention the disorder, disease or condition is caused by Clostridium botulinum, in particular botulism. In another specific embodiment of the present invention the disorder, disease or condition is caused by Clostridium difficile, in particular pseudomembranoes enterokolitis. In another specific embodiment of the present invention the disorder, disease or condition is caused by Bacillus anthracis, in particular cutaneous anthrax, inhalation anthrax, and gastrointestinal anthrax. In another specific embodiment of the present invention the disorder, disease or condition is caused by Enterococcus faecalis or E. faecium, like nosocomial infections, and endokarditis. In another specific embodiment of the present invention the disorder, disease or condition is caused by Bacillus cereus, in particular food poisonings, bronchial pneumonia, septicaemia and meningitis. In another specific embodiment of the present invention the disorder, disease or condition is caused by Mycobacterium avium, Mycobacterium paratuberculosis and Mycobacterium tuberculosis, in particular tuberculosis. In another specific embodiment of the present invention the disorder, disease or condition is caused by Mycoplasma pneumoniae, in particular pneumonia, diseases of the upper respiratory tract and inflammations of the ear drum. In another specific embodiment of the present invention the disorder, disease or condition is caused by Actinomyces, in particular actinomycosis in human, cattle, cat and dog. In another specific embodiment of the present invention the disorder, disease or condition is caused by Corynebacterium diphteriae, in particular localized diphtheria of the tonsils, the nose, the nasopharynx or the middle ear, progressive diphtheria of the larynx, the trachea and the bronchi, toxic or maligne diphtheria, skin and wound diphtheria.

The methods of eliminating, reducing or preventing bacterial biofilms by means of fusion proteins according to the present invention provide a possibility to invade into the bacterial biofilm and eliminate, reduce and prevent the bacterial biofilm.

The methods of eliminating, reducing or preventing bacterial biofilms by means of fusion proteins according to the present invention may be for the treatment and/or prevention of the following infections: wound infections, in particular wounds associated with diabetes mellitus, tonsillitis, osteomyelitis, bacterial endocarditis, sinusitis, infections of the cornea, urinary tract infection, infection of the biliary tract, infectious kidney stones, urethritis, prostatitis, catheter infections, middle-ear infections, formation of dental plaque, gingivitis, periodontitis, cystic fibrosis, and infections of permanent indwelling devices such as joint prostheses and heart valves.

In another preferred embodiment of eliminating, reducing and preventing bacterial biofilms by means of fusion proteins according to the present invention may be for the treatment and/or prevention of infections associated with foreign matter, like contamination and colonisation of catheters, implants and medical devices, in particular instruments, apparatus, endoscopes, dental devices, dialysis equipment, like peritoneal dialysis catheter, pacemaker, endotracheal tubes, voice prothesis, cerebrospinal fluid shunts, venous catheter, artificial heart valves and joint prothesis.

In another preferred embodiment of eliminating, reducing and preventing bacterial biofilms by means of fusion proteins according to the present invention the bacterial biofilm is formed by Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans.

In another preferred embodiment of eliminating, reducing and preventing bacterial biofilms by means of fusion proteins according to the present invention may be for the prevention or removal of contaminations in health care, agriculture, and industrial settings, in particular in water pipes of hospitals, in water, plumbing, ventilation, building heating, air conditioning, oil wells, cosmetics and medicaments.

In another preferred embodiment of eliminating, reducing and preventing bacterial biofilms by means of fusion proteins according to the present invention may be for the prevention of biocorrision, in particular in cooling circuits, water treatment plants, domestic hot water systems, power plants, production systems and machineries for automobiles, computers, colours, oil and gas.

In another preferred embodiment of eliminating, reducing and preventing bacterial biofilms by means of fusion proteins according to the present invention may be for the prevention of biofouling, in particular on submarine objects, ships, platforms, buoys, sensor systems for scientific or surveillance purposes in the maritime field.

In a preferred embodiment of the present invention a fusion protein according to the present invention is used for medical treatment, if the infection to be treated or prevented is caused by multiresistant bacterial strains associated with bacterial biofilm, in particular by strains resistant against one or more of the following antibiotics: streptomycin, tetracycline, cephalothin, gentamicin, cefotaxime, cephalosporin, ceftazidime or imipenem.

Furthermore, in the methods or the use of the present invention the fusion protein, preferably the endolysin variant, the autolysin variant or bacteriocin variant can be used, added or administered in combination or in addition with conventional antibacterial agents, such as antibiotics, lantibiotics, bacteriocins or endolysins. In another preferred embodiment, the antibiotics are added, used or administered in the methods and the use according to the present invention simoultaneous with the fusion protein, after or before the administration or addition of fusion protein.

In a preferred embodiment of the present invention the fusion protein can be used or administered in combination with at least one of the following antibiotics: β-lactams, aminoglycosides, fluoroquinolones, macrolides, novobiocin, rifampicin, oxazolidinones, fusidic acid, mupirocin, pleuromutilins, daptomycin, vancomycin, tetracyclines, sulfonamides, chloramphenicol, trimetoprim, fosfomycin, cycloserine and polymyxin.

In another preferred embodiment of the present invention the fusion protein can be used in methods of eliminating, reducing or preventing bacterial biofilms of Staphylococcus aureus by administering it in combination with at least one of the following antibiotics: β-lactams, aminoglycosides, fluoroquinolones, macrolides, novobiocin, rifampicin, oxazolidinones, fusidic acid, mupirocin, pleuromutilins, daptomycin, vancomycin, tetracyclines, sulfonamides, chloramphenicol, trimetoprim, fosfomycin and cycloserine.

In another preferred embodiment of the present invention a fusion protein can be used in methods of eliminating, reducing or preventing bacterial biofilms of Escherichia coli by administering it in combination with at least one of the following antibiotics: β-lactams, aminoglycosides, fluoroquinolones, tetracyclines, sulfonamides, chloramphenicol, trimetoprim, fosfomycin, cycloserine and polymyxin.

In another preferred embodiment of the present invention a fusion protein can be used in methods of eliminating, reducing or preventing bacterial biofilms of Pseudomonas aeruginosa by administering it in combination with at least one of the following antibiotics: β-lactams, aminoglycosides, fluoroquinolones and polymyxin.

The present invention also relates to a pharmaceutical pack for use of eliminating, reducing and preventing bacterial biofilm comprising one or more compartments, wherein at least one compartment comprises one or more fusion protein according to the present invention and/or one or more hosts transformed with a nucleic acid comprising a nucleotide sequence encoding a fusion protein according to the present invention or a composition according to the present invention.

In another aspect the present invention relates to a process of preparation of a pharmaceutical composition for use of eliminating, reducing and preventing bacterial biofilm, said process comprising admixing one or more fusion protein according to the present invention and/or one or more hosts transformed with a nucleic acid comprising a nucleotide sequence encoding a fusion protein according to the present invention with a pharmaceutically acceptable diluent, excipient or carrier.

In an even further aspect the composition according to the present invention is a cosmetic composition for use of eliminating, reducing and preventing bacterial biofilm. Several bacterial species can cause irritations on environmentally exposed surfaces of the patient's body such as the skin. In order to prevent such irritations or in order to eliminate minor manifestations of said bacterial pathogens, special cosmetic preparations may be employed, which comprise sufficient amounts of the fusion protein according to the present invention in order to degrade already existing or freshly settling pathogenic Gram-negative and/or Gram-positive bacteria.

In a further aspect the present invention relates to the fusion protein according to the present invention for use as diagnostic means in medicinal, food or feed or environmental diagnostics, in particular as a diagnostic means for the diagnostic of bacteria infection caused in particular by Gram-negative and/or Gram-positive bacteria associated with bacterial biofilm. In this respect the fusion protein according to the present invention may be used as a tool to specifically degrade pathogenic bacteria associated with bacterial biofilm, in particular Gram-negative and/or Gram-positive pathogenic bacteria. The degradation of the bacterial cells by the fusion protein according to the present invention can be supported by the addition of detergents like Triton X-100 or other additives which weaken the bacterial cell envelope like polymyxin B. Specific cell degradation is needed as an initial step for subsequent specific detection of bacteria using nucleic acid based methods like PCR, nucleic acid hybridization or NASBA (Nucleic Acid Sequence Based Amplification), immunological methods like IMS, immunofluorescence or ELISA techniques, or other methods relying on the cellular content of the bacterial cells like enzymatic assays using proteins specific for distinct bacterial groups or species (e.g. β-galactosidase for enterobacteria, coagulase for coagulase positive strains).

In a further aspect the present invention relates to the use of the fusion protein according to the present invention for the removal, reduction and/or prevention of Gram-negative and/or Gram-positive bacterial contamination associated with bacterial biofilm of foodstuff, of food processing equipment, of food processing plants, of surfaces coming into contact with foodstuff such as shelves and food deposit areas and in all other situations, where pathogenic, facultative pathogenic or other undesirable bacteria can potentially infest food material, of medical devices and of all kind of surfaces in hospitals and surgeries.

In particular, a fusion protein of the present invention may be used in methods of eliminating, reducing or preventing bacterial biofilms prophylactically as sanitizing agent. Said sanitizing agent may be used before or after surgery, or for example during hemodialysis. Moreover, premature infants and immunocompromised persons, or those subjects with need for prosthetic devices may be treated with a fusion protein according to the present invention. Said treatment may be either prophylactically or during acute infection. In the same context, nosocomial infections, especially by antibiotic resistant strains like Pseudomonas aeruginosa (FQRP), Acinetobacter species and Enterobacteriaceae such as E. coli, Salmonella, Shigella, Citrobacter, Edwardsiella, Enterobacter, Hafnia, Klebsiella, Morganella, Proteus, Providencia, Serratia and Yersinia species; Methicillin-resistant Staphylococcus aureus, Vancomycin-resistant Enterococcus faecalis, Vancomycin-resistant Enterococcus faecium, Streptococcus pneumoniae, Propionibacterium acnes, multidrug-resistant Mycobacterium tuberculosis, may be treated prophylactically or during acute phase with a fusion protein of the present invention. Therefore, a fusion protein according to the present invention may be used as a disinfectant to eliminate, reduce and prevent bacterial biofilms also in combination with other ingredients useful in a disinfecting solution like detergents, tensids, solvents, antibiotics, lantibiotics, or bacteriocins.

For the use of the fusion protein according to the present invention for eliminating, reducing or preventing bacterial biofilms as a disinfectant e.g. in hospital, dental surgery, veterinary, kitchen or bathroom, the fusion protein can be prepared in a composition in form of e.g. a fluid, a powder, a gel, or an ingredient of a wet wipe or a disinfection sheet product. Said composition may additionally comprise suitable carrier, additives, diluting agents and/or excipients for its respective use and form, respectively, —but also agents that support the antimicrobial activity like EDTA or agents enhance the antimicrobial activity of the fusion proteins. The fusion protein may also be used with common disinfectant agents like, Alcohols, Aldehydes, Oxidizing agents, Phenolics, Quaternary ammonium compounds or UV-light. For disinfecting for example surfaces, objects and/or devices the fusion protein can be applied on said surfaces, objects and/or devices. The application may occur for instance by wetting the disinfecting composition with any means such as a cloth or rag, by spraying, pouring. The fusion proteins may be used in varying concentration depending on the respective application and the “reaction time” intended to obtain full antimicrobial activity.

In a further aspect the present invention relates to the use of the fusion protein according to the present invention as a food additive.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter, however, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

The following examples explain the present invention but are not considered to be limiting. Unless indicated differently, molecular biological standard methods were used, as e.g., described by Sambrock et al., 1989, Molecular Cloning: A Laboratory Manual, 2nd edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.

EXAMPLE 1 Cloning, Expression and Purification of Modified phiKZgp144 and ELgpgp188 Endolysin Variants

phiKZgp144 as depicted in SEQ ID NO: 1 and ELgp188 as depicted in SEQ ID NO: 2 are modular endolysins originating from Pseudomonas aeruginosa phages φKZ and EL with an N-terminal peptidoglycan binding and C-terminal catalytic domain (Briers et al., 2007).

For the amplification of the open reading frame (ORF) of phiKZgp144 and ELgp188 PCR a standard 5′ primer (for phiKZgp144: 5′ ATGAAAGTATTACGCAAA 3′ (SEQ ID NO: 83); for ELgp188 5′ ATGAACTTCCGGACGAAG 3′ (SEQ ID NO: 65)) and the standard 3′ primers according to SEQ ID NO: 81 and 82 were applied (for phiKZgp144: TTTTCTATGTGCTGCAAC (SEQ ID NO: 81); for ELgp188: ATACGAAAT AACGTGACGA (SEQ ID NO: 82)) was used. To extend the 5′ end of the open reading frame encoding phiKZgp144 or ELgp188 with a gene fragment encoding nine positively charged residues (Lys-Arg-Lys-Lys-Arg-Lys-Lys-Arg-Lys—SEQ ID NO: 11) a tail PCR with an extended 5′ primer (for phiKZgp144: 5′ ATGGGATCCAAACGCAAGAAACGTAAGAAA CGCAAAAAAGTATTACGCAAAG 3′ (SEQ ID NO 79); for ELgp188: 5′ ATGGGATCCAAACGCAAGAAACGTAAGAAA CGCAAAAACTTCCGGACGAAG 3′ (SEQ ID NO: 80)) and the standard 3′ primers according to SEQ ID NO: 81 and 82 were applied. The PCR product was cloned in the pEXPSCT/TOPO® expression vector (Invitrogen, Carlsbad, Calif., USA) according to the protocol of the manufacturer. Arginine triplets were incorporated besides lysine triplets to avoid tRNA depletion and reduce the risk of frameshifts (the only two available triplets for lysine are AAA and AAG, leading to long A-stretches). Insertion of additional polycationic cassettes into the designed BamHI restriction site lengthens the tail with extra cationic residues. This insertion creates an arginine and serine triplet at each junction site (FIG. 1). Up to four polycationic peptides were fused to both phiKZgp144 and ELgp188, designated (POLY)^(n)-gp144 or (POLY)^(n)-gp188 (n=1, 2, 3, 4), comprising respectively 9, 19, 29 and 39 positively charged amino acid residues in the N-terminus. Accordingly, the following constructs were expressed in E. coli BL21 (DE3) pLysS cells (exponentially growing cells at 37° C., induction using 1 mM IPTG, expression for 4 h at 37° C.):

Number of positively Fusion protein SEQ ID NO: charged amino acid residues POLY-gp144 SEQ ID NO: 35 9 (POLY)²-gp144 SEQ ID NO: 36 19 (POLY)³-gp144 SEQ ID NO: 37 29 (POLY)⁴-gp144 SEQ ID NO: 38 39 POLY-gp188 SEQ ID NO: 39 9 (POLY)²-gp188 SEQ ID NO: 40 19 (POLY)³-gp188 SEQ ID NO: 41 29 (POLY)⁴-gp188 SEQ ID NO: 42 39

The modified endolysin variants POLY-gp144 (SEQ ID NO: 35), (POLY)²-gp144 (SEQ ID NO: 36), POLY-gp188 (SEQ ID NO: 39) and (POLY)²-gp188 (SEQ ID NO: 40) have been used for further investigations. Said proteins were purified by Ni²⁺ affinity chromatography using the C-terminal 6×His-tag (Akta Fast Protein Liquid Chromatography using 1 ml His-trap Ni-NTA columns). The total yields per liter E. coli expression culture were determined by spectrophotometric measurement of the protein concentration and the total volume of the purified stock solution. The purification of gp188 derivatives was performed under more stringent conditions (65 mM imidazole) compared to gp144 derivatives (50 mM imidazole) to ensure high purity. The total yields per liter E. coli expression culture are shown in table 5.

TABLE 5 Yields of recombinant purification of endolysin derivatives per liter E. coli expression culture. Endolysin Fusion phiKZgp144 ELgp188 POLY   2 mg   48 mg (POLY)² 0.5 mg 0.06 mg

Purified stock solutions were ˜90% pure. Mass spectrometric analysis of purified solutions of POLY-derivatives revealed traces of the E. coli SOS ribosomal subunit protein L2 and 16S rRNA uridine-516 pseudo-uridylate synthase. All phiKZgp144 derivatives showed multimer formation which could be converted to monomers by addition of β-mercaptoethanol, indicating that interdisulfide bonds cause multimerization.

EXAMPLE 2 Antibacterial Activity of Modified phiKZgp144 and ELgp188 Variants

Exponential (˜10⁶/ml) P. aeruginosa PAO1p cells (Pirnay J P et al. (2003), J Clin Microbiol., 41(3):1192-1202) were 100× diluted (final density was ˜10⁶/ml) and incubated at room temperature with each 10 μg undialyzed protein (unmodified endolysins phiKZgp144 (SEQ ID NO: 1) and ELpg188 (SEQ ID NO: 2) and modified endolysin variants POLY-gp144 (SEQ ID NO:35), (POLY)²-gp144 (SEQ ID NO: 36), POLY-gp188 (SEQ ID NO: 39) and (POLY)²-gp188 (SEQ ID NO: 40) at a final concentration of 100 μg/ml in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole). After 1 hour cell suspensions were diluted in PBS buffer (10e-5, 10e-4 and 10e-3) and plated (standard LB-medium, incubated overnight at 37° C.). Additionally, a negative control containing cells in PBS buffer was plated. The residual colonies were counted after an overnight incubation. Based on the counted cell numbers the antibacterial activity as the relative inactivation (%) (=100−(N_(i)/No)*100 with N₀=number of untreated cells and N_(i)=number of treated cells) and in logarithmic units (=log₁₀ N₀/N_(i)) was calculated (Table 6). All samples were replicated in six fold. Averages/standard deviations are represented. Statistical analysis was performed using a student's t-test.

Unmodified endolysins phiKZgp144 and ELgp188 do not reduce cell numbers significantly compared to the negative control. This observation illustrates the efficacy of the outer membrane as a barrier for the endolysin to degrade the cell wall of the Gram-negative bacteria. In contrast as shown in Table 6 the incubation with the modified endolysins POLY-gp144, (POLY)²-gp144, POLY-gp188 and (POLY)²-gp188 causes a significant reduction (α=0.05) of the bacterial cell number (99.85±0.09% for POLY-gp144 and 98.0±0.2% for POLY-gp188). An increase of the length of the polycationic peptide further tends to strengthen the antibacterial activity, especially in case of phiKZgp144 (a reduction up to 99.98±0.02% or 3.7±0.3 log units is achieved within 1 hour for (POLY)²-gp144). Moreover, the experiments demonstrated that the modified endolysins of phiKZgp144 have a higher antibacterial activity than the modified endolysins of ELgp188.

TABLE 6 Antibacterial effect of endolysins unmodified and modified phiKZgp144 and ELgp188 variants. Endolysins Exponentially phiKZgp144 ELgp188 growing cells % log % log unmodified  0 ± 15 0.00 ± 0.06  10 ± 13 0.05 ± 0.06 endolysin POLY 99.85 ± 0.09 2.9 ± 0.3 98.0 ± 0.2 1.7 ± 0.1 (POLY)² 99.98 ± 0.02 3.7 ± 0.3 98.9 ± 0.4 2.0 ± 0.2

Thus, the example demonstrated that the addition of a short peptide of nine cationic residues N-terminally to phiKZgp144 (SEQ ID NO: 1) is already sufficient to kill almost 99.9% of the cells within 1 hour. Poly-L-Lysine has intrinsic antibacterial activity as well, although this property is so far only ascribed to polymers of at least 20 residues (Vaara and Vaara, 1983a, 1983b). However, the concerted action of the polycationic peptide and the endolysin kills the cells.

In a further experiment the modified endolysin POLY-gp144 was dialyzed to 50 mM KH₂P0₄/K₂HP0₄ pH 7 and used instead of undialyzed protein solution as described above. Thereby, the inactivation level was additionally increased from 2.9±0.3 log units to 3.9±0.2 log units.

EXAMPLE 3 Expression of Modified phiKZgp144 and ELgp188 Variants in Pichia pastoris as a Host for Non-Toxic Recombinant Production

The open reading frame encoding POLY-gp144 (SEQ ID NO: 35) was cloned in the pPICZαA shuttle vector (Invitrogen), which was subsequently integrated in the P. pastoris genome by homologous recombination (as indicated by the manufacturer; P. pastoris X33 cells, Invitrogen). Gene expression was induced with methanol (1%) in BMMY-medium and the supernatant was analyzed for the presence of enzymatic activity after 1, 3 and 4 days. Therefore, an amount of 30 μl supernatant of the P. pastoris expression culture was added to 270 μl chloroform-permeabilized P. aeruginosa PAO1p cells (Pirnay J P et al. (2003), J Clin Microbiol., 41(3):1192-1202) after 1, 3 and 4 days (buffer condition: KH₂PO₄/K₂HP0₄ I=120 mM pH 6.2). Subsequently, the optical density was spectrophotometrically recorded (FIG. 2). A drop in optical density indicates the secretion of a muralytic enzyme by P. pastoris. As a negative control, P. pastoris X33 without expression plasmid was included. Thus, the lysis of the substrate upon addition of the supernatants sample is a measure for successful recombinant production and secretion of POLY-gp144 (SEQ ID NO: 35) by P. pastoris. After 1 day, a limited enzymatic activity could be detected. The maximum activity was observed after 3 days since no significant increase of activity in the supernatants was observed at the fourth day. No toxic effect on the cell density of P. pastoris was observed.

During expression by P. pastoris the α-secretion signal of the vector causes secretion of the recombinant protein to the surrounding media, which allows a simplify purification since only a limited number of other proteins is secreted. A BamHI restriction site in the 5′ end of the open reading frames enables the addition of more cassettes encoding additional polycationic peptides.

EXAMPLE 4 Further Modified Endolysin phiKZgp144 Variants with Different Polycationic Peptides

To test and to compare the potential of polycationic peptides variants of phiKZgp144 and other endolysin encoding genes were synthesised having different polycationic peptides at the N-terminal end of the protein. Peptide variation concerns length, composition and insertion of linker sequences. On the one hand further polycationic peptides having N-terminal multiples of the KRK motive were produced. On the other hand polycationic peptides consisting only of arginine (R) or lysine (K) were produced. Moreover, to enhance the translation of long polycationic peptides, polycationic peptides comprising a linker sequence were produced.

The different products were cloned in the pET32b expression vector (Novagen, Darmstadt, Germany). pET32b was used to reduce potential toxicity of the polycationic peptide against the E. coli host. A vector-encoded fusion protein (thioredoxin) masks the polycationic peptide and can be eliminated during the purification process.

Accordingly, the following modified endolysin variants were expressed in E. coli BL21 (DE3) cells at 37° C. until an optical density of OD600nm=0.6 was reached. Then protein expression was induced with 1 mM IPTG (final concentration) and expression was preformed for four hours. Then E. coli cells were harvested by centrifugation for 20 min at 6000 g and cell disruption and protein purification was performed according the S-tag purification kit (Novagen, Darmstadt, Germany):

Modified endolysin peptide variant length Sequence of the peptide phiKZgp144 0 — (SEQ ID NO: 1) pKKZ144pET32b 10 KRKKRKKRKK (SEQ ID NO: 43) (SEQ ID NO: 14) KRK_6_pET32b 6 KRKKRK (SEQ ID NO: 44) (SEQ ID NO: 10) KRK_12_pET32b 12 KRKKRKKRKKRK (SEQ ID NO: 45) (SEQ ID NO: 15) KRK_14_pET32b 14 KRKKRKKRKKRKKR (SEQ ID NO: 46) (SEQ ID NO: 16) R9_pET32b 9 RRRRRRRRR (SEQ ID NO: 47) (SEQ ID NO: 12) K8_pET32b 8 KKKKKKKK (SEQ ID NO: 48) (SEQ ID NO: 13) pK2KZ144_pET32b_mod3 38 KRKKRKKRKRGSGSGKRKKRKKRKGSGSGKRKKRKKRK (SEQ ID NO: 49) (SEQ ID NO: 28)

All proteins were purified using the S-Tag™ rEK Purification Kit (Novagen, Darmstadt, Germany). Using the pET32b vector, the expressed proteins were not toxic to the host resulting in high yields of produced protein. Purified stock solutions showed high purity.

Exponential (˜10⁶/ml) P. aeruginosa PAO1p cells (Burn wound isolate, Queen Astrid Hospital, Brussels; Pirnay J P et al. (2003), J Clin Microbiol., 41(3):1192-1202) were 100× diluted (final density was ˜10⁶/ml) incubated at room temperature with each 10 μg undialyzed protein as listed above at a final concentration of 100 μg/ml in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole). After 1 hour cell suspensions were diluted 1:100 and plated on LB. Additionally, a negative control was plated using buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole). The residual colonies were counted after an overnight incubation at 37° C. Based on the counted cell numbers the antibacterial activity as the relative inactivation (%) (=100−(N_(i)/No)*100 with N_(o)=number of untreated cells and N_(i)=number of treated cells) was calculated (Table 7). All samples were replicated at least in four fold.

TABLE 7 Antibacterial effect of endolysins unmodified and modified phiKZgp144 and ELgp188 Modified endolysin Reduction variant Sequence of the peptide [%] phiKZgp144 (SEQ ID  0 NO: 1) pKKZ144pET32b KRKKRKKRKK 99-99.9 (SEQ ID NO: 43) (SEQ ID NO: 14) KRK_6_pET32b KRKKRK 99.9 (SEQ ID NO: 44) (SEQ ID NO: 10) KRK_12_pET32B KRKKRKKRKKRK 99-99.9 (SEQ ID NO: 45) (SEQ ID NO: 15) KRK_14_pET32b KRKKRKKRKKRKKR 99.9 (SEQ ID NO: 46) (SEQ ID NO: 16) R9_pET32b RRRRRRRRR 99 (SEQ ID NO: 47) (SEQ ID NO: 12) K8_pET32b KKKKKKKK 99 (SEQ ID NO: 48) (SEQ ID NO: 13) pK2KZ144_pET32b_mod3 KRKKRKKRKRGSGSGKRKKRKKRKGSGSGKRKKRKKRK 99.9 (SEQ ID NO: 49) (SEQ ID NO: 28)

Unmodified phiKZgp144 does not reduce cell numbers significantly compared to the negative control. Beyond that, modified phiKZgp144 variants wearing a polycationic peptide of N-terminal multiples of the KRK motive enhance the antimicrobial effect immensely. However, also variants having a homomer peptide of lysine or arginine show significant reduction of cells compared with unmodified phiKZgp144 as measured. Moreover, also the variant having a polycationic peptide of 38 amino acid residues and comprising a linker sequence enhance the antimicrobial effect immensely.

EXAMPLE 5 Modified Endolysin Variants of Salmonella typhimurium Phage PSP3

PSP3gp10 according to SEQ ID NO: 8 is a globular endolysin with 165 amino acid residues originating from Salmonella typhimurium phage PSP3 with a catalytic lambda-like muramidase domain. As predicted by BLASTp and Pfam analysis the PSP3gp10 endolysin comprises its catalytic domain in the range of about amino acid residue 34 to about amino acid residue 152.

Purified genomic DNA of phage PSP3 was used as a template for the amplification of the open reading frame (ORF) of PSP3gp10 in a Hot Start Taq polymerase PCR reaction (Qiagen, Germany) using the following PCR parameters:

For said PCR a standard 5′ primer (5′ ATGGGATCCCCGGTCATTAATACTCACCAG 3′(SEQ ID NO: 50)) and a standard 3′ primer (5′ TGCCATCACCCCGCCAGCCGTG 3′ (SEQ ID NO: 51)) was used. To extend the 5′ end of the ORF which encodes PSP3gp10 with a gene fragment encoding the polycationic 9-mer peptide Lys-Arg-Lys-Lys-Arg-Lys-Lys-Arg-Lys (SEQ ID NO: 11) a tail PCR (Hot Start Taq polymerase PCR with same parameters) with an extended 5′ primer (5′ ATGGGATCCAAACGCAAGAAACGTAA GAAACGCAAACCGGTCATTAATACTCACCAG 3′ (SEQ ID NO: 52)) and the standard 3′ primer according to SEQ ID NO: 51 was applied. Both the original unmodified PSP3gp10 PCR fragment and the PK-extended fragment were ligated in the pEXPSCT/TOPO® expression vector (Invitrogen, Carlsbad, Calif., USA) by following the TA-cloning protocol of the manufacturer.

Recombinant expression of PSP3gp10 according to SEQ ID NO: 8 and PKPSP3gp10 according to SEQ ID NO: 53 is performed in exponentially growing E. coli BL21 (λDE3) pLysS cells (Invitrogen) after induction with 1 mM IPTG (isopropylthiogalactoside) at 37° C. for a period of 4 hours. Both proteins were purified by Ni²⁺ affinity chromatography (Akta FPLC, GE Healthcare) using the C-terminal 6×His-tag, encoded by the pEXPSCT/TOPO® expression vector. The Ni²⁺ affinity chromatography is performed in 4 subsequent steps, all on room temperature:

-   -   1. Equilibration of the Histrap HP 1 ml column (GE Healthcare)         with 10 column volumes of Washing Buffer (60 mM imidazole, 0.5         mM NaCl and 20 mM NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5         ml/min.     -   2. Loading of the total lysate (with wanted endolysin) on the         Histrap HP 1 ml column at a flow rate of 0.5 ml/min.     -   3. Washing of the column with 15 column volumes of Washing         Buffer at a flow rate of 1 ml/min.     -   4. Elution of bounded endolysin from the column with 10 column         volumes of Elution

Buffer (500 mM imidazole, 5 mM NaCl and 20 mM NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5 ml/min

The total yields of both purified recombinant proteins per liter E. coli expression culture shown in Table 8. The values were determined by spectrophotometric measurement of the protein concentration and the total volume of the purified stock solution at a wavelength of 280 nm. Purified stock solutions consisting of PSP3gp10 and PKPSP3gp10, respectively, in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 500 mM imidazole) were at least 90% pure as determined visually on SDS-PAGE gels.

TABLE 8 Yields of purified recombinant PSP3gp10 endolysin and its modified variant PKPSP3gp10 per liter E. coli expression culture. Endolysins Expression yield PSP3gp10 (SEQ ID NO: 8) 2.15 mg PKPSP3gp10 (SEQ ID NO: 53) 5.56 mg

To determine the anti-Gram-negative spectrum of the PKPSP3gp10 endolysin according to SEQ ID NO: 53, a combination of 1.315 μM PKPSP3gp10 endolysin and 0.5 mM EDTA was tested on the clinical P. aeruginosa strains PAO1p and Br667, Escherichia coli WK6, and Salmonella typhimurium (see Table 9). Exponential growing bacterial cells (OD_(600nm) of 0.6) were 100-fold diluted to a final density of about 10⁶/ml of each strain were incubated for 30 minutes at room temperature without shaking with unmodified endolysin PSP2gp10 (SEQ ID NO: 8) and modified endolysin PKPSP3gp10 (SEQ ID NO: 53) each in combination without and with 0.5 mM EDTA. For incubation, the endolysins were used each in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole) and the incubation took place at a final concentration of endolysin of 1.315 μM. As a control each strain was also incubated for 30 minutes with 0.5 mM EDTA (in same buffer as outlined above) but no endolysin.

TABLE 9 List of used Gram-negative strains Gram-negative strain Source Reference Pseudomonas aeruginosa Burn wound isolate, Queen Pirnay et al., PAO1p Astrid Hospital, Brussels 2003* Pseudomonas aeruginosa Burn wound isolate, Queen Pirnay et al., Br667 Astrid Hospital, Brussels 2003* Escherichia coli WK6 Standard laboratory Prof. C. Michiels expression strain Salmonella typhimurium SGSC N° 2317 Prof. C. Michiels LT2 *Pirnay JP et al. (2003). Molecular epidemiology of Pseudomonas aeruginosa colonization in a burn unit: persistence of a multidrug-resistant clone and a silver sulfadiazine-resistant clone. J Clin Microbiol., 41(3): 1192-1202.

After incubation cell suspensions were diluted three times (respectively 10⁵-10⁴-10³ cells/ml) and 100 μl of each dilution was plated out on LB-medium. The residual colonies were counted after an overnight incubation on 37° C. Based on the counted cell numbers the antibacterial activity as the relative inactivation in logarithmic units (=log₁₀ N₀/N_(i) with N₀=number of untreated cells and N_(i)=number of treated cells) was calculated (Table 10).

TABLE 10 Antibacterial activity of unmodified endolysin (PSP3gp10) and its modified endolysin variant (PKPSP3gp10) with and without EDTA-Na₂ on different exponential growing Gram-negative species. 1.315 μM 1.315 μM 1.315 μM 1.315 μM PSP3gp10 + PKPSP3gp10 + 0.5 mM EDTA PSP3gp10 PKPSP3gp10 0.5 mM EDTA 0.5 mM EDTA P. aeruginosa 0.146 +/− 0.002 0.383 +/− 0.015 0.344 +/− 0.163 3.552 +/− 0.536 >4.146 PAO1p P. aeruginosa 0.223 +/− 0.038 0.375 +/− 0.056 0.353 +/− 0.086 0.571 +/− 0.035 0.891 +/− 0.118 Br667 Salmonella 0.104 +/− 0.049 0.283 +/− 0.038 0.327 +/− 0.057 0.690 +/− 0.036 0.850 +/− 0.032 typhimurium Escherichia coli 0.393 +/− 0.035 0.190 +/− 0.029 0.205 +/− 0.088 0.387 +/− 0.014 0.584 +/− 0.024 WK6

All samples were replicated in threefold. Averages +/− standard deviations are represented. The maximal reduction observed is dependent on the detection level of 10 cells/ml and the initial cell density. For PAO1p, EDTA works synergistically with both the unmodified PSP3gp10 endolysin and its modified variant PKPSP3gp10.

EXAMPLE 6 Modified Endolysin Variants of Escherichia coli Phage P2

P2gp09 according to SEQ ID NO: 9 is a globular endolysin of 165 amino acid residues originating from Escherichia coli phage P2 with a catalytic lambda-like muramidase domain. As predicted by BLASTp and Pfam analysis the P2gp09 endolysin comprises its catalytic domain in the range of about amino acid residue 34 to about amino acid residue 152.

Purified genomic DNA of phage P2 was used as a template for the amplification of the open reading frame (ORF) of P2gp09 in standard PCR reaction with Pfu polymerase (Fermentas) using the following PCR parameters:

For said PCR a standard 5′ primer (5′ ATGGGATCCCCGGTAATTAACACGCATC 3′ (SEQ ID NO: 54)) and a standard 3′ primer (5′ AGCCGGTACGCCGCCAGCGGTACGC 3′ (SEQ ID NO: 55)) was used. To extend the 5′ end of the ORF which encodes P2gp09 with a gene fragment encoding the polycationic 9-mer peptide Lys-Arg-Lys-Lys-Arg-Lys-Lys-Arg-Lys (SEQ ID NO: 11) a tail PCR (with same parameters as standard PCR above) with an extended 5′ primer (5′ ATGGGATCCAAACGCAAGAAACGTAAGAAACGC AAACCGGTAATTAACACGCATC 3′ (SEQ ID NO: 56) and the standard 3′ primer according to SEQ ID NO 55 was applied. Both the original unmodified P2gp09 PCR fragment and the extended fragment were ligated in the pEXPSCT/TOPO® expression vector (Invitrogen, Carlsbad, Calif., USA) by following the TA-cloning protocol of the manufacturer. Recombinant expression of P2gp09 according to SEQ ID NO: 9 and PKP2gp09 according to SEQ ID NO: 57 is performed in exponentially growing E. coli BL21 (λDE3) pLysS cells (Invitrogen) after induction with 1 mM IPTG (isopropylthiogalactoside) at 37° C. for a period of 4 hours. Both proteins were purified by Ni²⁺ affinity chromatography (Akta FPLC, GE Healthcare) using the C-terminal 6×His-tag, encoded by the pEXPSCT/TOPO® expression vector. The Ni²⁺ affinity chromatography is performed in 4 subsequent steps, all on room temperature:

-   -   1. Equilibration of the Histrap HP 1 ml column (GE Healthcare)         with 10 column volumes of Washing Buffer (60 mM imidazole, 0.5         mM NaCl and 20 mM NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5         ml/min.     -   2. Loading of the total lysate (with wanted endolysin) on the         Histrap HP 1 ml column at a flow rate of 0.5 ml/min.     -   3. Washing of the column with 15 column volumes of Washing         Buffer at a flow rate of 1 ml/min.     -   4. Elution of bounded endolysin from the column with 10 column         volumes of Elution Buffer (500 mM imidazole, 5 mM NaCl and 20 mM         NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5 ml/min

The total yields of both purified recombinant proteins per liter E. coli expression culture shown in Table 11. The values were determined by spectrophotometric measurement of the protein concentration and the total volume of the purified stock solution at a wavelength of 280 nm. Purified stock solutions consisting of P2gp09 and PKP2gp09, respectively, in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 500 mM imidazole) were at least 95% pure as determined visually on SDS-PAGE gels.

TABLE 11 Yields of purified recombinant P2gp09 endolysin and its PK-modified derivative PKP2gp09 per liter E. coli expression culture. Endolysins Expression yield P2gp09 (SEQ ID NO: 9) 5.52 mg PKP2gp09 (SEQ ID NO: 57) 3.40 mg

To determine the anti-Gram-negative spectrum of the PK2gp09 endolysin according to SEQ ID NO: 57, a combination of 1.315 μM PK2gp09 endolysin and 0.5 mM EDTA was tested on the clinical P. aeruginosa strains PAO1p and Br667, Burkholderia pseudomallei, Pseudomonas putida G1 and on Escherichia coli WK6 (see Table 13). Exponential growing bacterial cells (OD_(600nm) of 0.6) were 100-fold diluted to a final density of about 10⁶/ml of each strain was incubated for 30 minutes at room temperature without shaking with unmodified endolysin P2gp09 (SEQ ID NO: 9) and modified endolysin PKP2gp09 (SEQ ID NO: 57) each in combination without and with 0.5 mM EDTA. For incubation, the endolysins were used each in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole) and the incubation took place at a final concentration of endolysin of 1.315 μM. As a control each strain was also incubated for 30 minutes with 0.5 mM EDTA (in same buffer as outlined above) but no endolysin. After incubation cell suspensions were diluted three times (respectively 10⁵-10⁴-10³ cells/ml) and 100 μl of each dilution was plated out on LB-medium. The residual colonies were counted after an overnight incubation on 37° C. Based on the counted cell numbers the antibacterial activity as the relative inactivation in logarithmic units (=log₁₀ N₀/N_(i) with N₀=number of untreated cells and N_(i)=number of treated cells, both counted after incubation) was calculated (Table 12).

TABLE 12 Antibacterial activity of unmodified endolysin (P2gp09) and its modified endolysin variant (P2gp09) with and without EDTA-Na₂ on different exponential growing Gram-negative species. 1.315 μM 1.315 μM 1.315 μM 1.315 μM P2gp09 + PKP2gp09 + 0.5 mM EDTA P2gp09 PKP2gp09 Δ 0.5 mM EDTA 0.5 mM EDTA Δ P. aeruginosa 0.330 +/− 0.146 0.374 +/− 0.084 0.326 +/− 0.069 −0.038 2.840 +/− 0.079 3.172 +/− 0.056 0.332 PAO1p P. aeruginosa 0.003 +/− 0.051 0.246 +/− 0.042 0.300 +/− 0.062 0.054 0.582 +/− 0.074 0.952 +/− 0.213 0.370 Br667 P. putida G1 0.072 +/− 0.084 0.419 +/− 0.024 1.014 +/− 0.139 0.595 3.919 +/− 0.118 >4.386 >0.467 Burkholderia 0.206 +/− 0.151 0.769 +/− 0.110 1.163 +/− 0.073 0.394 3.890 +/− 0.056 4.255 +/− 0.001 0.365 pseudomallei Escherichia 0.153 +/− 0.046 0.751 +/− 0.053 1.104 +/− 0.039 0.353 0.784 +/− 0.071 1.545 +/− 0.102 0.749 coli WK6

All samples were replicated in threefold. Averages +/− standard deviations are represented. The maximal reduction observed is dependent on the detection level of 10 cells/ml and the initial cell density.

TABLE 13 List of used Gram-negative strains Gram-negative strain Source Reference Pseudomonas aeruginosa Burn wound isolate, Queen Pirnay et al., PAO1p Astrid Hospital, Brussels 2003* Pseudomonas aeruginosa Burn wound isolate, Queen Pirnay et al., Br667 Astrid Hospital, Brussels 2003* Burkholderia Clinical isolate, UZ Prof J. Verhaegen pseudomallei Gasthuisberg, Leuven Escherichia coli WK6 Standard laboratory Prof C. Michiels expression strain Pseudomonas putida G1 Soil isolate, Moskow Prof V. Krylov *Pirnay JP et al., (2003). Molecular epidemiology of Pseudomonas aeruginosa colonization in a burn unit: persistence of a multidrug-resistant clone and a silver sulfadiazine-resistant clone. J Clin Microbiol., 41(3): 1192-1202.

EXAMPLE 7 Modified Endolysin Variants of Pseudomonas putida Phage OBP

OBPgpLYS according to SEQ ID NO: 7 is a modular endolysin of 328 amino acid residues originating from Pseudomonas putida phage OBP with a putative N-terminal peptidoglycan binding domains and a C-terminal catalytic chitinase domain. As predicted by BLASTp and Pfam analysis the OBPgpLYS endolysin comprises its catalytic domain in the range of about amino acid residue 126 to about amino acid residue 292 and the N-terminal peptidoglycan binding domain in the range of about amino acid residues 7 to 96.

Purified genomic DNA of phage OBP was used as a template for the amplification of the open reading frame (ORF) of OBPgpLYS in standard PCR reaction with Pfu polymerase (Fermentas, Ontario, Canada) using the following PCR parameters:

Therefore a standard 5′ primer (5′ ATGAAAAATAGCGAGAAGAAT 3′ (SEQ ID NO: 58)) and a standard 3′ primer (5′ AACTATTCCGAGTGCTTTCTTTGT 3′ (SEQ ID NO: 59)) was used. To extend the 5′ end of the ORF which encodes OBPgpLYS with a gene fragment encoding the polycationic 9-mer peptide Lys-Arg-Lys-Lys-Arg-Lys-Lys-Arg-Lys- (SEQ ID NO: 11) a tail PCR (with same parameters as standard PCR above) with an extended 5′ primer (5′ ATGGGATCCAAACGCAAGAAACGTAAGAAACGCAAAAAAAATAGCGAG AAGAAT 3′ (SEQ ID NO: 60)) and the standard 3′ primer according to SEQ ID NO 59 was applied. Both the original unmodified OBPgpLYS PCR fragment and the extended fragment were ligated in the pEXPSCT/TOPO® expression vector (Invitrogen, Carlsbad, Calif., USA) by following the TA-cloning protocol of the manufacturer.

Recombinant expression of OBPgpLYS according to SEQ ID NO: 7 and PKOBPgpLYS according to SEQ ID NO: 61 is performed in exponentially growing E. coli BL21 (λDE3) pLysS cells (Invitrogen) after induction with 1 mM IPTG (isopropylthiogalactoside) at 37° C. for a period of 4 hours. Both proteins were purified by Ni²⁺ affinity chromatography (Akta FPLC, GE Healthcare) using the C-terminal 6×His-tag, encoded by the pEXPSCT/TOPO® expression vector. The Ni²⁺ affinity chromatography is performed in 4 subsequent steps, all on room temperature:

-   -   1. Equilibration of the Histrap HP 1 ml column (GE Healthcare)         with 10 column volumes of Washing Buffer (60 mM imidazole, 0.5         mM NaCl and 20 mM NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5         ml/min.     -   2. Loading of the total lysate (with wanted endolysin) on the         Histrap HP 1 ml column at a flow rate of 0.5 ml/min.     -   3. Washing of the column with 15 column volumes of Washing         Buffer at a flow rate of 1 ml/min.     -   4. Elution of bounded endolysin from the column with 10 column         volumes of Elution Buffer (500 mM imidazole, 5 mM NaCl and 20 mM         NaH₂P0₄-NaOH on pH 7.4) at a flow rate of 0.5 ml/min

The total yields of both purified recombinant proteins per liter E. coli expression culture shown in Table 14. The values were determined by spectrophotometric measurement of the protein concentration and the total volume of the purified stock solution at a wavelength of 280 nm. Purified stock solutions consisting of OBPgpLYS and PKOBPgpLYS, respectively, in Elution Buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 500 mM imidazole) were at least 90% pure as determined visually on SDS-PAGE gels.

TABLE 14 Yields of purified recombinant OBPgpLYS endolysin and its PK-modified derivative PKOBPgpLYS per liter E. coli expression culture. Endolysins Expression yield OBPgpLYS (SEQ ID NO: 7) 3.3 mg PKOBPgpLYS (SEQ ID NO: 61) 4.7 mg

To determine the anti-Gram-negative spectrum of the PKOBPgpLYS endolysin according to SEQ ID NO: 61, a combination of 1.313 μM PK OBPgpLYS endolysin and 0.5 mM EDTA was tested on the clinical multiresistant P. aeruginosa strain Br667, Pseudomonas putida G1 (host of phage OBP) and a range of other Gram-negative pathogens (Escherichia coli WK6, Salmonella typhimurium LT2 and Burkholderia pseudomallei) (see Table 16). Exponential growing bacterial cells (OD_(600nm) of 0.6) were 100-fold diluted to a final density of about 10⁶/ml of each strain was incubated for 30 minutes at room temperature without shaking with unmodified endolysin OBPgpLYS (SEQ ID NO: 7) and modified endolysin PKOBPgpLYS (SEQ ID NO: 61) each in combination without and with 0.5 mM EDTA. For incubation, the endolysins were used each in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole) and the incubation took place at a final concentration of endolysin of 1.313 μM. As a control each strain was also incubated for 30 minutes with 0.5 mM EDTA (in same buffer as outlined above) but no endolysin. After incubation cell suspensions were diluted three times (respectively 10⁵-10⁴-10³ cells/ml) and 100 μl of each dilution was plated out on LB-medium. The residual colonies were counted after an overnight incubation on 37° C. Based on the counted cell numbers the antibacterial activity as the relative inactivation in logarithmic units (=log₁₀ N₀/N_(i) with N₀=number of untreated cells and N_(i)=number of treated cells, both counted after incubation) was calculated (Table 15). All samples were replicated in threefold. Averages +/− standard deviations are represented. The maximal reduction observed is dependent on the detection level of 10 cells/ml and the initial cell density.

TABLE 15 Antibacterial activity of unmodified endolysin (OBPgpLYS) and its modified endolysin variant (PKOBPgpLYS) with and without EDTA-Na₂ on different exponential growing Gram-negative species. 1.313 μM 1.313 μM 1.313 μM 1.313 μM OBPgpLYS + PKOBPgpLYS + 0.5 mM EDTA OBPgpLYS PKOBPgpLYS 0.5 mM EDTA 0.5 mM EDTA P. aeruginosa 0.130 +/− 0.023 2.531 +/− 0.173 3.079 +/− 0.015 4.357 +/− 1.857 >5.687 PAO1p P. aeruginosa 0.031 +/− 0.023 1.082 +/− 0.083 1.163 +/− 0.063 3.144 +/− 0.223 5.272 +/− 0.573 Br667 P. putida G1 0.412 +/− 0.055 0.141 +/− 0.027 0.904 +/− 0.079 4.891 +/− 0.000 >4.891 Burkholderia 0.220 +/− 0.081 0.997 +/− 0.131 1.806 +/− 0.287  4.08 +/− 0.301 >4.861 pseudomallei Escherichia coli 0.592 +/− 0.113 0.681 +/− 0.032 1.434 +/− 0.018 1.179 +/− 0.200 1.695 +/− 0.147 WK6 Salmonella 0.054 +/− 0.048 0.076 +/− 0.011 0.127 +/− 0.013 0.774 +/− 0.052 0.908 +/− 0.037 typhimurium

TABLE 16 List of used Gram-negative strains Gram-negative strain Source Reference Pseudomonas aeruginosa Burn wound isolate, Queen Pirnay et al., PAO1p Astrid Hospital, Brussels 2003* Pseudomonas aeruginosa Burn wound isolate, Queen Pirnay et al., Br667 Astrid Hospital, Brussels 2003* Pseudomonas putida G1 Soil isolate, Moskow Prof V. Krylov Burkholderia Clinical isolate, UZ Prof J. Verhaegen pseudomallei Gasthuisberg, Leuven Escherichia coli WK6 Standard laboratory Stratagene expression strain Salmonella typhimurium SGSC N° 2317 Prof C. Michiels LT2 *Pirnay JP, De Vos D, Cochez C, Bilocq F, Pirson J, Struelens M, Duinslaeger L, Cornelis P, Zizi M, Vanderkelen A. (2003). Molecular epidemiology of Pseudomonas aeruginosa colonization in a burn unit: persistence of a multidrug-resistant clone and a silver sulfadiazine-resistant clone. J Clin Microbiol., 41(3): 1192-1202.

While the global efficacy of the OBPgpLYS treatment is species dependent, the results in table 16 show an added effect of the PKOBPgpLYS compared to unmodified OBPgpLYS for all bacterial species tested, both in the absence as the presence of 0.5 mM EDTA. For Pseudomonas and Burkholderia species, a clear synergistic effect with EDTA is observed for the PKOBPgpLYS activity.

EXAMPLE 8 Effect of Different EDTA Concentration on the Antibacterial Activity of OBPgpLYS and PKOBPgpLYS

To determine the influence of EDTA on the antibacterial activity of unmodified and modified endolysins the antibacterial activity of the unmodified OBPgpLYS endolysin (SEQ ID NO: 7) and the PKOBPgpLYS endolysin (SEQ ID NO: 61) was tested on Pseudomonas aeruginosa PAO1p cells (Pirnay J P et al. J Clin Microbiol., 41(3):1192-1202 (2003)) using different concentrations of EDTA and endolysins. Exponential growing bacterial cells (OD_(600nm) of 0.6) were 100-fold diluted to a final density of about 10⁶/ml and incubated for 30 minutes at room temperature without shaking with unmodified endolysin OBPgpLYS (SEQ ID NO: 7) and modified endolysin PKOBPgpLYS (SEQ ID NO: 61). For incubation, the endolysins were used each in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole) at final concentrations of endolysin of 0.013 μM, 0.131 μM and 1.315 μM. Thereby, the following different EDTA concentrations were used: 0 mM, 0.05 mM, 0.5 mM and 10 mM. As a control one sample was also incubated for 30 minutes with no endolysin, instead of there was buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole) added. After incubation cell suspensions were diluted three times (respectively 10⁵-10⁴-10³ cells/ml) and 100 μl of each dilution was plated out on LB-medium. The residual colonies were counted after an overnight incubation on 37° C. Based on the counted cell numbers the antibacterial activity as the relative inactivation in logarithmic units (=log₁₀N₀/N_(i) with N₀=number of untreated cells and N_(i)=number of treated cells, both counted after incubation) was calculated (Table 17). All samples were replicated in threefold. Averages +/− standard deviations are represented. The maximal reduction observed (5.69 log units) is dependent on the detection level of 10 cells/ml and the initial cell density. “Δ” gives the difference of activity between the respective OBPgpLYS and PKOBPgpLYS samples.

TABLE 17 Antibacterial activity of unmodified endolysin (OBPgpLYS) and its modified endolysm variant (PKOBPgpLYS) in combination with different EDTA concentrations on exponential growing Pseudomonas aeruginosa PAO1p cells Concentration of EDTA-Na₂ (in mM) 0 0.05 0.5 10 No endolysin / 0.028 +/− 0.008 0.130 +/− 0.023 1.827 +/− 0.052 0.013 μM OBPgpLYS 0.956 +/− 0.110 / 4.626 +/− 0.287 / 0.013 μM PKOBPgpLYS 0.992 +/− 0.181 / 5.204 +/− 0.000 / Δ 0.036   0.578 0.131 μM OBPgpLYS 2.158 +/− 0.027 / 4.599 +/− 0.275 / 0.131 μM PKOBPgpLYS 2.529 +/− 0.184 / 5.671 +/− 0.000 / Δ 0.371   1.072 1.315 μM OBPgpLYS 2.531 +/− 0.173 2.762 +/− 0.091 4.357 +/− 1.857 4.888 +/− 0.275 1.315 μM PKOBPgpLYS 3.079 +/− 0.015 4.145 +/− 0.015 >5.687 >5.687 Δ 0.548 1.383 >1.330 >0.799

As shown in Table 17 unmodified endolysin OBPgpLYS reduces cell numbers significantly with more than 2.5 log units for 1.315 μM and with +/−1 log unit for 0.013 μM, compared to the negative control. Modified endolysin PKOBPgpLYS results in an added 0.5 log units reduction for exponentially growing PAO1p cells. The observed antibacterial effect can be increased to more as 5.69 log units reduction (beneath the detection level) by combining PKOBPgpLYS with the outer membrane permeabilizer EDTA-Na₂ at a concentration of 0.5 and 10 mM EDTA. The difference in activity between the unmodified OBPgpLYS and the PK-modified OBPgpLYS increases by raising the amount of added endolysin (from 0.013-1.315 μM endolysin).

EXAMPLE 9 Antibacterial Activity of Modified phiKZgp144 Variants on Different Gram-Negative Bacteria

To test and to compare the potential of polycationic peptides variants of phiKZgp144 and other endolysins, encoding genes were synthesised having polycationic peptides at the N-terminal end of the protein.

The different products were cloned in the pET32b expression vector (Novagen, Darmstadt, Germany). pET32b was used to reduce potential toxicity of the polycationic peptide against the E. coli host. A vector-encoded fusion protein (thioredoxin) masks the polycationic peptide and can be eliminated during the purification process.

The genes encoding smi01 (YP_001712536) and KRK9_smi01 (SEQ ID NO: 75) were fully synthesised (Entelechon, Regensburg, Germany) and cloned into pET32b.

Accordingly, the following modified endolysin variants were expressed in E. coli BL21 (DE3) cells at 37° C. until an optical density of OD600nm=0.6 was reached: smi01 (YP_001712536), KRK9_smi01 (SEQ ID NO: 75), phiKZgp144 (SEQ ID NO: 1), pKKZ144pET32b (SEQ ID NO: 43) and POLYKZ144 (SEQ ID NO: 35). Protein expression was induced with 1 mM IPTG (final concentration) and expression was preformed for four hours. Then E. coli cells were harvested by centrifugation for 20 min at 6000 g and cell disruption and protein purification was performed using the S-Tag™ rEK Purification Kit (Novagen, Darmstadt, Germany). Using the pET32b vector, the expressed proteins were not toxic to the host resulting in high yields of produced protein. Purified stock solutions showed high purity.

For testing and as reference for comparison phiKZgp144 and POLYgp144 were synthesized and purified as described in EXAMPLE 1.

Exponential (˜10⁶/ml) growing cells of P. aeruginosa PAO1p (Burn wound isolate, Queen Astrid Hospital, Brussels; Pirnay J P et al. (2003), J Clin Microbiol., 41(3):1192-1202), Acinetobacter baumannii (DSMZ 30007) or Burkholderia solanaceum (Isolate provided by Prof. C. Michiels) were 100× diluted (final density was ˜10⁶/ml) incubated at room temperature with each 10 μg undialyzed protein as listed above at a final concentration of 100 μg/ml in buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole). After 1 hour cell suspensions were diluted 1:100 and plated on LB. Additionally, a negative control was plated using buffer (20 mM NaH₂P0₄-NaOH pH7.4; 0.5 M NaCl; 0.5 M imidazole). The residual colonies were counted after an overnight incubation at 37° C. Based on the counted cell numbers the antibacterial activity as the relative inactivation (%) (=100−(N_(i)/No)*100 with N₀=number of untreated cells and N_(i)=number of treated cells) was calculated (Table 18). All samples were replicated at least in four fold.

TABLE 18 Antibacterial effect of different modified endolysin variants (NCBI numbers in brackets) on different bacterial species Reduction Protein Bacterial species [%] smi01 Acinetobacter baumannii DSMZ 30007 0 (YP_001712536) KRK9_smi01 Acinetobacter baumannii DSMZ 30007 50 phiKZgp144 Pseudomonas aeruginosa 0 pKKZ144pET32b Pseudomonas aeruginosa 99-99.9 phiKZgp144 Acinetobacter baumannii DSMZ 30007 0 pKKZ144pET32b Acinetobacter baumannii DSMZ 30007 99.9 phiKZgp144 Burkholderia solanacearum 0 POLYKZ144 Burkholderia solanacearum 99-99.9

Unmodified endolysins phiKZgp144 and smi01 (YP_001712536) do not reduce cell numbers significantly compared to the negative control. This observation again illustrates the efficacy of the outer membrane as a barrier for the endolysin to degrade the cell wall of the Gram-negative bacteria. In contrast as shown in Table 18 the incubation with the modified endolysins KRK9_smi01, pKKZ144pET32b and POLY-gp144 causes a significant reduction of the bacterial cell number on Acinetobacter baumannii (50% for KRK_smi01; 99.9% for pKKZ144pET32b), Pseudomonas aeruginosa (90-99.9% for pKKZ144pET32b) and Burkholderia solanaceum (90-99.9% for POLYKZ144).

These experiments demonstrate the applicability of the cationic/polycationic fusion approach for other endolysins. Moreover, the experiments demonstrated that the modified endolysins are active on a variety of bacteria.

EXAMPLE 10 Reduction of Pseudomonas aeruginosa Biofilm

In the present experiment the antimicrobial activity of the modified endolysin variants SMAP29-KZ144 and PK-OBP, of the endolysins OBP and KZ144 and of the peptide PK was tested against the biofilm of the Pseudomonas aeruginosa strains 2572 and 2573.

Biofilm reduction was quantified using crystal violet assay (Peeters et al., J Microbiol Methods 72: 157-165 (2008)).

Biofilm Formation:

Overnight liquid cultures of a mucoid strain of, Pseudomonas aeruginosa 2572 (patient isolate), Pseudomonas aeruginosa 2573 and a non-mucoid E. coli BL21(DE3) were diluted to OD600=0.1. A polystyrene 96-well plate was inoculated with 100 μl culture/well. After 4 h incubation at 37° C. supernatant was discarded and adherent bacteria were washed using 100 μl physiological saline (PS). Inoculated wells were filled with 100 μl liquid LB media and incubated for an additional 24 h period. After discarding the supernatant the developed biofilm was washed again with 100 μl PS.

Biofilm Treatment:

Biofilm was treated using 50 μg/well PKKZ144 or 20 u/well alginate lyase or 50 μg/well SMAP29-KZ144 and KZ144 or 25 μg/well PK-OBP and OBP or 1.25 μg PK-Peptide (all in buffer with 500 mM NaCl) diluted one part to one part 2×LB (without NaCl) media and incubated for 12 h. Untreated series were done as negative controls (one part protein buffer to one part 2×LB without NaCl). After discarding the supernatant the developed biofilm was washed again with 100 μl PS.

Biofilm Quantification:

The washed biofilm was fixed with 300 μl methanol (99%; 15 min) and air-dried. Staining was done using 100 μl 0.3% crystal violet. After 20 min wells were rinsed with tap water and 300 μl 33% acetic acid was used dissolving the bound crystal violet out of extracellular matrix of the biofilm. After 20 min 1:10 dilution was made and absorption (590 nm) was measured.

Statistical analysis showed a massive reduction of detected biofilm using PKKZ144 compared to alginate lyase-treated or untreated inoculates. Using PKKZ144 it was possible to reduce the biofilm to the level of a non-mucoid E. coli lab strain.

Also the modified endolysin variants SMAP29-KZ144 and PK-OBP showed massive reduction of the Pseudomonas aeruginosa biofilm compared to the endolysins OBP and KZ144. Contrarily, the PK-peptide seems to enhance the formation of the Pseudomonas aeruginosa biofilm.

EXAMPLE 11 Reduction of Acinetobacter baumannii Biofilm

In the present experiment the antimicrobial activity of the modified endolysin variant PK-OBP, of the endolysin OBP and of the peptide PK was tested against the biofilm of the Acinetobacter baumannii strain DSMZ30007.

Biofilm reduction was quantified using crystal violet assay (Peeters et al., J Microbiol Methods 72: 157-165 (2008)).

The biofilm formation, treatment and quantification were perfomed as described in Example 10.

The modified endolysin variant PK-OBP showed massive reduction of the Acinetobacter baumannii biofilm compared to the endolysin OBP. Contrarily, the PK-peptide seems to enhance the formation of the Acinetobacter baumannii biofilm.

EXAMPLE 12 Reduction of Staphylococcus aureus Biofilm

In the present experiment the antimicrobial activity of the fusion proteins Ply2638-PK and PK-Lysostaphin, of the enzymes Lysostaphin and Ply2638 and of the peptide PK was tested against the biofilm of the Staphylococcus aureus strain KS13.

Biofilm reduction was quantified using crystal violet assay (Peeters et al., J Microbiol Methods 72: 157-165 (2008)).

The biofilm formation, treatment and quantification were perfomed as described in Example 10. Except that for the biofilm treatment, 25 μg/well Ply2638A-PK and Ply2638A or 18 μg/well PK-Lysostaphin and Lysostaphin or 1.25 μg PK-Peptide was used

The fusion proteins PK-Lysostaphin and PK-Ply2638 showed massive reduction of the Staphylococcus aureus biofilm compared to the enzymes Lysostaphin and Ply2638. Contrarily, the PK-peptide seems to enhance the formation of the Staphylococcus aureus biofilm.

EXAMPLE 13 Reduction of Listeria monocytogenes Biofilm

In the present experiment the antimicrobial activity of the modified endolysin variant Pentapeptide-Ply511 was tested against the biofilm of the Listeria monocytogenes strain ScottA.

Biofilm reduction was quantified using crystal violet assay (Peeters et al., J Microbiol Methods 72: 157-165 (2008)).

The biofilm formation, treatment and quantification were perfomed as described in Example 10. Except that for the biofilm treatment, 25 μg/well Pentapeptide-Ply511 was used.

The modified endolysin variant PK-Ply511 showed massive reduction of the Listeria monocytogenes biofilm. 

The invention claimed is:
 1. A method of eliminating or reducing an existing bacterial biofilm comprising: (a) providing a fusion protein comprising a phiKZgp 144 endolysin according to SEQ ID NO: 1, to which a peptide comprising the amino acid sequence of SEQ ID NO:94 is fused; and (b) contacting a material, liquid, surface or biological material containing the bacterial biofilm with said fusion protein to effect membrane or LPS disruption in said bacterial biofilm, thereby eliminating or reducing the bacterial biofilm.
 2. The method according to claim 1, wherein said peptide is fused to the N- and/or the C-terminus of the endolysin.
 3. A method of eliminating or reducing an existing bacterial biofilm comprising: (a) providing a fusion protein comprising the amino acid sequence of SEQ ID NO: 139; and (b) contacting a material, liquid, surface or biological material containing the bacterial biofilm with said fusion protein to effect membrane or LPS disruption in said bacterial biofilm, thereby eliminating or reducing the bacterial biofilm.
 4. The method according to claim 1, wherein the material contacted with the fusion protein is a stone, rocks, soil, sediments, food, feed or cosmetics.
 5. The method according to claim 1, wherein the liquid contacted with the fusion protein is water.
 6. The method according to claim 5, wherein water is drinking water, ground water or waste water, hot spring, sea, lake, river, any kind of aqueous system, cleaning and storage solutions of contact lenses, dentures, implants, prothesis or braces.
 7. The method according to claim 1, wherein the liquid contacted with the fusion protein is any substance derived or obtained from a living organism.
 8. The method according to claim 1, wherein the liquid contacted with the fusion protein is surface of medical devices, of industrial or potable water system piping and of natural aquatic systems.
 9. The method according to claim 1, wherein in combination or in addition to the fusion protein antibiotics can be added.
 10. The method according to claim 3, wherein said peptide is fused to the N- and/or the C-terminus of the endolysin.
 11. The method according to claim 3, wherein the material contacted with the fusion protein is a stone, rocks, soil, sediments, food, feed or cosmetics.
 12. The method according to claim 3, wherein the liquid contacted with the fusion protein is water.
 13. The method according to claim 12, wherein water is drinking water, ground water or waste water, hot spring, sea, lake, river, any kind of aqueous system, cleaning and storage solutions of contact lenses, dentures, implants, prothesis or braces.
 14. The method according to claim 3, wherein the liquid contacted with the fusion protein is any substance derived or obtained from a living organism.
 15. The method according to claim 3, wherein the liquid contacted with the fusion protein is surface of medical devices, of industrial or potable water system piping and of natural aquatic systems.
 16. The method according to claim 3, wherein in combination or in addition to the fusion protein antibiotics can be added. 